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T. Murray, Kimberly, Andrew J. Read, and Andrew R. Solow. "The use of time/area closures to reduce bycatches of harbour porpoises: lessons from the Gulf of Maine sink gillnet fishery." J. Cetacean Res. Manage. 2, no. 2 (September 1, 2000): 135–41. http://dx.doi.org/10.47536/jcrm.v2i2.497.
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In 1994, the United States National Marine Fisheries Service (NMFS) implemented a series of time/area closures for the Gulf of Maine sink gillnet fishery to reduce the bycatch of harbour porpoises (Phocoena phocoena). The present study evaluates the effectiveness of the Mid-Coast closure area, implemented during November 1994. Rates of porpoise bycatches are analysed prior to, during and after the closure. In addition, individual vessels are tracked and the spatial distribution of fishing effort examined to determine how fishermen responded to the closure. The highest bycatch rate occurred in September in the Mid-Coast region, well before the closure. During November, fishermen concentrated much of their effort adjacent to the closed area in unrestricted waters, where bycatch occurred. The Mid-Coast closure was not in place for a long enough period, nor was it large enough, to be effective in reducing bycatch rates of harbour porpoises. The failure of the Mid-Coast closure is attributed to temporal and spatial variation in patterns of bycatch rates, and to the displacement of fishing effort and porpoise bycatch outside the closed area.
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Lesage, Veronique, Joanne Keays, Samuel Turgeon, and Sylvain Hurtubise. "Bycatch of harbour porpoises (Phocoena phocoena) in gillnet fisheries of the Estuary and Gulf of St. Lawrence, Canada, 2000-02." J. Cetacean Res. Manage. 8, no. 1 (March 8, 2023): 67–78. http://dx.doi.org/10.47536/jcrm.v8i1.703.
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The incidental catch of harbour porpoises (Phocoena phocoena) in the gillnet fishery of the Estuary and Gulf of St. Lawrence, Canada, was examined using: (1) questionnaires mailed to fishermen inquiring about bycatches in 2000 and 2001 (n=2,277 or 44% of the fishermen with valid licenses); and (2) using data from an at-sea observer programme and sentinel fishery programme in 2001 and 2002. The questionnaire survey had a low response rate (22%) and provided bycatch estimates of 2,215 (95% CI 1,151-3,662) and 2,394 (95% CI 1,440-3,348) porpoises in 2000 and 2001, respectively. The low number of hauls monitored by at-sea observers prevented the estimation of bycatch levels for several zones and the study area as a whole, and provided only imprecise estimates for all other zones. The results from questionnaires indicated a 24-63% reduction in harbour porpoise bycatches since the late 1980s, whereas the at-sea observer programme provided bycatch levels for 2001 and 2002 that were unreliable and underestimated, approaching one quarter of those documented in the late 1980s. Although both indices indicated a decrease in bycatches since the late 1980s, the magnitude of this change remains uncertain given the weaknesses associated with the two approaches. Considering the maximum population rate of increase (Rmax) for harbour porpoises as 4% and the lower and upper 95% confidence limits (1,440-3,348) of our most reliable estimate of bycatches (i.e. the 2001 questionnaire survey results), the harbour porpoise population in the Gulf of St. Lawrence would need to be at least 36,000-83,700 individuals for current incidental catches to be sustainable. If the rate of increase is less than maximal, e.g. 0.5Rmax or 2%, then 72,000-167,400 harbour porpoises would be needed to attain sustainability. Kingsley and Reeves (1998) estimated that an average 36,000 to 125,000 porpoises occupied the Gulf of St. Lawrence during the summers of 1995 and 1996. Although the trajectory of the population since it was last surveyed in 1996 is uncertain, these findings suggest that bycatch levels might remain a cause for concern for the harbour porpoise population in the Gulf of St. Lawrence. The results from the comparison between the sentinel fishery and the commercial fishery subjected and not subjected to at-sea observations suggest that fine-scale temporal and spatial changes in fishing activities may greatly affect harbour porpoise bycatch levels.
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Winther, Morten. "Bycatches of harbour porpoises (Phocoena phocoena L.) in Danish set-net fisheries." J. Cetacean Res. Manage. 1, no. 2 (January 25, 1999): 123–35. http://dx.doi.org/10.47536/jcrm.v1i1.457.
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Data on bycatch of harbour porpoise (Phocoena phocoena L.) in the commercial Danish set-net fisheries were sampled from 5,591km nets in the period 1992 to 1998 using independent observers. A total bycatch of 325 harbour porpoises was reported. Cluster analysis was used to stratify the sampled fishing trips and official catch statistics into a number of different m6tiers defined by the target species for the trips. Extrapolation of the observed bycatch rate to total fish landings of the Danish set-net fleet gave an average annual bycatch of 6,785 (CV 0.12) for the North Sea fisheries in the period 1994-1998. Sampling was not sufficient to estimate total bycatch for other areas. Bycatch was observed in Kattegat but not in the Baltic Sea. Generalised Linear Models were used to identify significant factors for bycatch in the North Sea. The bycatch rate, given as number per length of nets x soak time, was significantly lower in fisheries for flatfish compared to roundfish fisheries. The highest bycatch rate was in the cod fishery over wrecks and no bycatch was observed in the sole fishery. Significant seasonal variation of bycatch was identified with the highest bycatch rate in the first and third quarter of the year. Bycatch rates had not changed in the observed period and there was no significant difference in bycatch rates between sub-areas.
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Gray, Charles A., and Steven J. Kennelly. "Bycatches of endangered, threatened and protected species in marine fisheries." Reviews in Fish Biology and Fisheries 28, no. 3 (May 29, 2018): 521–41. http://dx.doi.org/10.1007/s11160-018-9520-7.
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Cullet, Philippe, and Annie Patricia Kameri‐Mbote. "Dolphin bycatches in Tuna Fisheries: A smokescreen hiding the real issues?" Ocean Development & International Law 27, no. 4 (January 1996): 333–48. http://dx.doi.org/10.1080/00908329609546088.
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Faruque, Hasan, and Hiroyuki Matsuda. "Conservative Scoring Approach in Productivity Susceptibility Analysis Leads to an Overestimation of Vulnerability: A Study from the Hilsa Gillnet Bycatch Stocks of Bangladesh." Fishes 6, no. 3 (August 24, 2021): 33. http://dx.doi.org/10.3390/fishes6030033.
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Despite different approaches used to assign the risk scores for missing information in productivity susceptibility analysis (PSA)—a widely used semi-quantitative risk assessment tool for target and non-target fisheries stocks—for the selected attributes of a given species, no formal comparison has been made between scoring approaches in terms of how well they can predict species vulnerability. The present study evaluated the PSA findings of 21 bycatch stocks of the Hilsa (Tenualosa ilisha) gillnet fishery of Bangladesh using two different scoring approaches (the conservative scoring approach, CSA; and the alternative scoring approach, ASA) to determine the most reliable approach to minimize false estimates of species vulnerability. Our analysis revealed that the V scores increased by 0.0−0.20 with a mean value of 0.09 for 21 selected bycatches when CSA was applied. The inconsistency between the vulnerability (V)-score-suggested fishing status (V ≤ 1.8 = underfishing, V > 1.8 = overfishing) and the fishing status defined by exploitation rate (E > 0.5 = overfishing, E < 0.5 = underfishing) were 38.1% and 19.0% under CSA and ASA, respectively. Likewise, the consistency between the V-score-suggested fishing status and fishers’ perceived catch trends was found to be higher when using ASA than when using CSA. Our analysis suggests that CSA could overestimate species vulnerability. Therefore, ASA is more reliable than CSA in PSA, which may increase the confidence of fisheries stakeholders in PSA.
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Szostek, Claire L., Lee G. Murray, Ewen Bell, Gwladys Lambert, and Michel J. Kaiser. "Regional variation in bycatches associated with king scallop (Pecten maximus L.) dredge fisheries." Marine Environmental Research 123 (February 2017): 1–13. http://dx.doi.org/10.1016/j.marenvres.2016.11.006.
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Östman, Örjan, Göran Sundblad, Peter Ljungberg, Sandra Levin, Martina Blass, Marju Kaljuste, Iris Dahlin, Rebecka Svensson, and Jens Olsson. "Catches, bycatches and stock indicators of fisheries targeting cyprinids along the Swedish Baltic Sea coast." Fisheries Research 268 (December 2023): 106829. http://dx.doi.org/10.1016/j.fishres.2023.106829.
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Herinirina, Patricia A., Lionel Bigot, Patrick Frouin, Huguette T. E. Volandrae, Roddy M. Randriatsara, Faustinato Behivoke, Lantoasinoro Ranivoarivelo, and Marc Léopold. "Seagrass macroinvertebrate bycatches support mosquito net trawl fishery in Madagascar." Aquatic Living Resources 36 (2023): 18. http://dx.doi.org/10.1051/alr/2023014.
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The use of mosquito nets, primarily for targeting small and/or juvenile fish, has rapidly increased in Western Indian Ocean shallow seagrass beds and coral reefs over the last 20 years. However, to date, invertebrate by-catch by locally-made fishing gear has not been reported. We studied the mosquito net trawl fishery in seagrass areas in the Bay of Toliara, Southwest Madagascar through the GPS tracking of fishers from August 2018 to February 2019. Catches were monitored through monthly landing surveys to characterize spatial temporal patterns in the abundance and diversity of macroinvertebrates in the seagrass beds. Fishing was carried out at low tide, mostly at night, by fishers pulling a hand-made trawl net of varying dimensions. Overall, 43 macroinvertebrate taxa were identified out of 217,080 individuals collected from 109 catch samples. Catches were generally composed of crustaceans (mainly Portunidae, Processidae, Penaeidae, and Alpheidae). The crab Thalamita mitsiensis largely dominated the abundance and biomass of the macroinvertebrate assemblage (from 6% to 100% and from 5 to 100% of the overall density and biomass, respectively). Macroinvertebrates composed 1.5% to 100% of the total catch per trip (i.e., 4–55 kg trip−1). They were sold for human consumption or animal feed, which provided additional income to fishers (USD 1–24 trip−1 and 1–72% of catch income per trip). This study revealed that macroinvertebrate resources provide valuable by-catch to small-scale fishers in Southwest Madagascar. This bycatch generates income that further encourages the use of mosquito net trawls and exacerbates their negative effects on coastal seagrass ecosystems and fisheries.
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Cox, Tara M., Andrew J. Read, Andrew Solow, and Nick Tregenza. "Will harbour porpoises (Phocoena phocoena) habituate to pingers?" J. Cetacean Res. Manage. 3, no. 1 (May 25, 2023): 81–86. http://dx.doi.org/10.47536/jcrm.v3i1.904.
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Large bycatches of harbour porpoises (Phocoena phocoena) occur in gillnet fisheries throughout the Northern Hemisphere. Several mitigation measures, including acoustic deterrent devices or ‘pingers’, have been used in efforts to reduce this bycatch. The potential exists for harbour porpoises to habituate to pingers, thus reducing their effectiveness over time. A field experiment was conducted to test the hypothesis that porpoises habituate to the sound produced by pingers. Porpoise echolocation and movements were monitored around a mooring equipped with a pinger (Dukane NetMark™ 1000) for three months in summer 1998 in the Bay of Fundy. Using a mean-shift model it was estimated that porpoises were initially displaced 208m from the pinger (p = 0.019), but this displacement diminished by 50% within four days (p = 0.019). Using a probability model it was demonstrated that the probability of porpoises within 125m of the pinger initially decreased when the pinger was turned on, but then increased to equal the control in 10-11 days. Echolocation rate (p < 0.001) and occurrence (p < 0.001) were significantly reduced in the vicinity of the pinger. These results indicate that porpoises habituated to the Dukane NetMark™ 1000 pinger and are not alerted to echolocate in the presence of nets by pingers.
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IMBIRIBA, Luan Campos, Diego Maia ZACARDI, Severino Adriano de Oliveira LIMA, and Raniere Garcez Costa SOUSA. "LENGTH-WEIGHT RELATIONSHIP OF THE SIX MOST ABUNDANT FISH SPECIES IN PRAWN FISHERY SEMI-FIXED TRAP BYCATCHES IN THE LOWER AMAZON REGION (PARÁ, BRAZIL)." Boletim do Instituto de Pesca 47 (2021): e628. http://dx.doi.org/10.20950/10.20950/1678-2305/bip.2021.47.e628.
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In this study, the length-weight relationships (LWR) were estimated for six fish species captured during prawn fishing in the Lower Amazon region (Pará, Brazil). Prawn fishing boosts the socioeconomic development of riverine communities and is a relevant activity as a source of income and subsistence in this region. In addition, we registered new LWRs for the species Ossancora punctata and Hypoptopoma elongatum. The samplings were performed in prawn catches monthly from February 2018 to January 2019, using a “matapi”, which consists of a semi‑fixed trap that has a galvanized iron structure (2.5 m height by 2.0 m in length) and nylon mesh (1.40 x 1.60 mm mesh), and has two tapered openings to facilitate the entry and trapping of the prawn. The results show that 75% of the fish caught as prawn bycatches had not yet reached sexual maturity. Thus, it is clear that fisheries need to develop fishing gear that allow small fish to escape from the traps during the prawn fishery.
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Escalle, Lauriane, Daniel Gaertner, Pierre Chavance, Alicia Delgado de Molina, Javier Ariz, and Bastien Mérigot. "Forecasted consequences of simulated FAD moratoria in the Atlantic and Indian Oceans on catches and bycatches." ICES Journal of Marine Science 74, no. 3 (December 13, 2016): 780–92. http://dx.doi.org/10.1093/icesjms/fsw187.
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Given the increasingly extensive use of drifting fish aggregation devices (FADs) by the purse-seine fisheries targeting tropical tunas, fishing effort restrictions have been introduced to manage tropical tuna stocks. However, these measures are focused on the protection of juvenile tunas and do not take account of the potential impact on bycatch or associated megafauna (whales and whale sharks). An iterative “fishing-day” Monte Carlo simulation model was developed to investigate the consequences on tropical tunas and bycatch of introducing extensive area 6-month moratoria on FAD activities. The model allowed for variability in a range of plausible values of the parameters characterizing the fishing operations conducted by European purse-seiners in the eastern tropical Atlantic and western Indian Oceans for the period 2005–2014. Monte Carlo simulations, using probabilities based on these fishery data, were carried out for the French and Spanish fishing fleets separately to account for differences in fishing strategies. The models predicted a decrease in FAD sets and an increase in free school sets. As a consequence, the catch of small tuna (<10 kg) decreased while the catch of large tuna (≥10 kg) increased, leading to an overall increase in tuna catch of 100–200 tons/year/vessel in the Atlantic Ocean, and a decrease of 400–1500 tons/year/vessel in the Indian Ocean. The bycatch decreased in the Indian Ocean, while in the Atlantic Ocean billfishes, turtles and chondrichthyans bycatch increased slightly and other bony fishes decreased. Because fishing practices were modified, whale and whale shark associated sets increased slightly in the Indian Ocean.
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Osawa, Yumiko, Takehiro Okuda, and Mai Miyamoto. "Bathymetric segregation among demersal benthos and its contributions to the differences in the bycatches on bottom fisheries in the Emperor Seamounts area, Northwestern Pacific Ocean." Regional Studies in Marine Science 68 (December 2023): 103261. http://dx.doi.org/10.1016/j.rsma.2023.103261.
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Louhichi, Maissa, Alexandre Girard, and Imed Jribi. "Fishermen Interviews: A Cost-Effective Tool for Evaluating the Impact of Fisheries on Vulnerable Sea Turtles in Tunisia and Identifying Levers of Mitigation." Animals 13, no. 9 (May 4, 2023): 1535. http://dx.doi.org/10.3390/ani13091535.
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Fisheries bycatch is considered one of the main threats to sea turtles. To provide an updated assessment of the bycatch impact on loggerhead turtles in Tunisia, 483 interviews were conducted with fishermen in 19 ports along the Gulfs of Gabes and Hammamet. The interview questions included data on vessel and fishing gear characteristics, monthly fishing effort, and monthly sea turtle bycatch of the last year. Results revealed that sea turtle bycatch per unit effort (BPUE) was the highest for ray nets (0.73 turtles/vessel/day, 95% CI [0.02–1.15]), followed by pelagic longlines (0.6 turtles/vessel/day, 95% CI [0–4.23]) and shark nets (0.4 turtles/vessel/day, 95% CI [0–2.12]). However, due to the trawlers’ high fishing effort, the cumulative impact of the trawl nets was the highest with an estimated number of 11,740 (95% CI [0–41,525.75]) turtles caught per year in Tunisia. Factors influencing the bycatch risk were gear characteristics (mesh size for nets, hook size for longlines, vertical opening for trawls), as well as season and location of operations. These factors will guide the research of mitigation solutions. The interviews with fishermen proved to be a cost-effective approach for the rapid assessment of sea turtle interactions with fisheries in the context of Tunisia.
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Werner, Timothy B., Simon Northridge, Kate McClellan Press, and Nina Young. "Mitigating bycatch and depredation of marine mammals in longline fisheries." ICES Journal of Marine Science 72, no. 5 (May 2015): 1576–86. http://dx.doi.org/10.1093/icesjms/fsv092.
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Abstract Demersal and pelagic longline fisheries involve frequent and geographically widespread interactions with many individuals, populations, and species of marine mammals. Animals sometimes suffer mortality and serious injury following these interactions, attracted mainly to longlines as a source of food. This depredating behaviour can have serious consequences for fishermen, especially when they lose valuable catch and face other associated operational and regulatory challenges. Using input from a group of international experts in the science, fishing industry, and government sectors, we produced a list of methods for mitigating depredation and bycatch of marine mammals in longline fisheries, collectively assessed their potential as a solution, and determined priorities for further research. The intention of this review is to help synthesize our current understanding about potential solutions, to provide an introduction to the articles that appear in this themed set of the ICES Journal of Marine Science, and to help fishermen, fisheries managers, and research scientists advance solutions to this global problem.
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Wang, John, Joel Barkan, Shara Fisler, Carlos Godinez-Reyes, and Yonat Swimmer. "Developing ultraviolet illumination of gillnets as a method to reduce sea turtle bycatch." Biology Letters 9, no. 5 (October 23, 2013): 20130383. http://dx.doi.org/10.1098/rsbl.2013.0383.
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Fisheries bycatch of marine animals has been linked to population declines of multiple species, including many sea turtles. Altering the visual cues associated with fishing gear may reduce sea turtle bycatch. We examined the effectiveness of illuminating gillnets with ultraviolet (UV) light-emitting diodes for reducing green sea turtle ( Chelonia mydas ) interactions. We found that the mean sea turtle capture rate was reduced by 39.7% in UV-illuminated nets compared with nets without illumination. In collaboration with commercial fishermen, we tested UV net illumination in a bottom-set gillnet fishery in Baja California, Mexico. We did not find any difference in overall target fish catch rate or market value between net types. These findings suggest that UV net illumination may have applications in coastal and pelagic gillnet fisheries to reduce sea turtle bycatch.
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Putri, Hanifa Miranda I. H., I. Wayan Arthana, Elok Faiqoh, Ranny R. Yuneni, and Yuniarti K. Pumpun. "Karakteristik Sosial Ekonomi Nelayan Pemanfaat Hiu Tikus (Alopiidae) di Manggis, Karangasem, Bali." Journal of Marine and Aquatic Sciences 8, no. 2 (February 1, 2023): 297. http://dx.doi.org/10.24843/jmas.2022.v08.i02.p14.
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Thresher sharks are known to have substantial economic value. They are caught globally as target and as bycatch in tuna fisheries. Due to their declining population, they are listed as an appendix II species on CITES, therefore any form of trade and fisheries related to the species have been nationally and internationally regulated. However, information on thresher shark fisheries in Bali is still limited. This study aims to socio-economically characterize thresher shark fishermen in Manggis, Karangasem. The research was conducted in August 2020 – October 2020 by interviewing 53 out of 119 recorded shark fishermen using a structured questionnaire. Shark fishermen use surface longlines to catch thresher sharks (Alopiidae) in between 3 areas, North Nusa Penida-Karangasem, east Nusa Penida and Bangko-Bangko. The fishermen catch sharks exclusively during the months of June-October and catch tuna the rest of the year. Operational costs for 1 boat ranges between Rp 121.000 – Rp 250.000 during 1 round trip. The income generated from shark fishing each trip averages to about Rp 627.714 per boat. Prior to the Covid-19 pandemic, some of the fishermen work jobs in the tourism sector. However, due to the pandemic’s impact on tourism, they have no choice but to be fishermen full time. Although thresher shark fisheries in Manggis are generally small scale, conservation and management strategies need to be implemented to ensure sustainable use of shark resources.
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Kaplan, Isaac C., Daniel S. Holland, and Elizabeth A. Fulton. "Finding the accelerator and brake in an individual quota fishery: linking ecology, economics, and fleet dynamics of US West Coast trawl fisheries." ICES Journal of Marine Science 71, no. 2 (September 4, 2013): 308–19. http://dx.doi.org/10.1093/icesjms/fst114.
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Abstract Isaac C. Kaplan, Daniel S. Holland, and Elizabeth A. Fulton. 2014. Finding the accelerator and brake in an individual quota fishery: linking ecology, economics, and fleet dynamics of US West Coast trawl fisheries. – ICES Journal of Marine Science, 71: 308–319. In 2011, the Pacific Fisheries Management Council implemented an individual transferrable quota (ITQ) system for the US West Coast groundfish trawl fleet. Under the ITQ system, each vessel now receives transferrable annual allocations of quota for 29 groundfish species, including target and bycatch species. Here we develop an ecosystem and fleet dynamics model to identify which components of an ITQ system are likely to drive responses in effort, target species catch, bycatch, and overall profitability. In the absence of penalties for discarding over-quota fish, ITQs lead to large increases in fishing effort and bycatch. The penalties fishermen expect for exceeding quota have the largest effect on fleet behaviour, capping effort and total bycatch. Quota prices for target or bycatch species have lesser impacts on fishing dynamics, even up to bycatch quota prices of $50 kg−1. Ports that overlap less with bycatch species can increase effort under individual quotas, while other ports decrease effort. Relative to a prior management system, ITQs with penalties for exceeding quotas lead to increased target species landings and lower bycatch, but with strong variation among species. The model illustrates how alternative fishery management policies affect profitability, sustainability and the ecosystem.
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Annida, Shafira Bilqis, Zulkarnain, Ronny Irawan Wahju, Charles P. H. Simanjuntak, Faqih Baihaqi, Tri Prabowo, and Muhammad Syarif Budiman. "Fish catches diversity of the glass eel fishery in Cikaso and Cimandiri estuaries, Sukabumi, Indonesia." E3S Web of Conferences 322 (2021): 03007. http://dx.doi.org/10.1051/e3sconf/202132203007.
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Cikaso and Cimandiri estuaries are well known as the central area of glass eel fisheries in Sukabumi Regency. Local fishermen catch glass eels using two main fishing gears, namely traps and lift nets. Although both fishing gears' target operation is glass eels, many other fish species are also caught as bycatch. The present study aimed to identify glass eels and bycatch ichthyofauna in glass eel fisheries of the Cikaso and Cimandiri estuaries, Sukabumi. The research was carried out monthly from November 2020 to January 2021. Glass eels fishing gears collected a total of 21 fish species belonging to 15 families in both estuaries. According to the percentage ano-dorsal length measurement to total length (AD/TL), 3 species of glass eel were identified, i.e. Anguilla bicolor bicolor, A. nebulosa, and A. marmorata. These three species were the most abundant fish catches in both estuaries. More than 18 bycatch ichthyofauna were recorded and most of them are economically important fish, such as Ambassidae, Eleotridae, Engraulidae, Gobiidae, and Polinemidae. To sustain fishery management, the recording bycatch from glass eel fishery in the Cikaso and Cimandiri estuaries is necessary to be done regularly because they contribute to fishing mortality.
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Karnad, Divya, Mayuresh Gangal, and Krithi K. Karanth. "Perceptions matter: how fishermen's perceptions affect trends of sustainability in Indian fisheries." Oryx 48, no. 2 (September 25, 2013): 218–27. http://dx.doi.org/10.1017/s0030605312001251.
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AbstractIndian marine fisheries have expanded four-fold in the last 50 years in the form of open-access commons. Although studies predict that fish stocks are on the decline there is little evidence that these declines are being countered by changes in either fishing regulations or fishing practices. Fishermen rarely comply with regulations, instead operationalizing and directing the fishery on their own. In these circumstances understanding how fishermen perceive and use resources has significant management and policy implications. Our study examined fishermen's perceptions about the state of fish stocks and documents current fishing practice and management strategies in India. We surveyed 342 fishermen in two states, Tamil Nadu and Maharashtra. We found that 86% of fishermen perceived a decline in catch and 69% perceived a decline in bycatch. Fishermen adapt to these declines by increasing fishing area and time spent, changing their gear, and overlapping in fishing zones. The convoluted interactions between ineffective community and state regulations guiding their actions has prevented fishermen from developing successful models of sustainable fisheries management. We identified non-compliance with regulations and government incentives as an important livelihood opportunity. Non-compliance drives change in fishing practice by giving fishermen the flexibility to respond to perceived fish catch dynamics by modifying their practices. We recommend strengthening local fishing communities by enabling them to enforce fishing regulations locally and by scaling back of existing government incentives, to protect the sustainability of these fisheries.
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Drakopulos, Lauren. "New Materialist Approaches to Fisheries." Environment and Society 11, no. 1 (September 1, 2020): 100–114. http://dx.doi.org/10.3167/ares.2020.110107.
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For the past 40 years, bycatch has been a significant focus of fisheries science and management, yet bycatch has evaded clear definition persisting as a perennial fisheries concern. This article brings insights from new materialism to examine the ontological politics of bycatch. Building on new materialist approaches to oceans and fisheries, the article contributes to the bycatch debate by putting forth a new framework for understanding bycatch as multiple, enacted through the material-discursive practices of science and policy. Through a survey of policy and scientific documents, the article traces the emergence of “bycatch” as a global fisheries issue. The analysis broadens the orderings and normative understandings about human and nonhuman life inflected by post-humanist and new materialist traditions, as well as fisheries science and policy.
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Fox, CH, C. Robertson, PD O’Hara, R. Tadey, and KH Morgan. "Spatial assessment of albatrosses, commercial fisheries, and bycatch incidents on Canada’s Pacific coast." Marine Ecology Progress Series 672 (August 19, 2021): 205–22. http://dx.doi.org/10.3354/meps13783.
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Fisheries bycatch mortality poses a primary threat to the majority of the world’s 22 albatross species, 15 of which are at risk of extinction. Although quantitative estimates of albatross bycatch are often unavailable due to a relative or total absence of monitoring, spatial overlap between fisheries and albatrosses is often used to estimate the extent of interaction, a proxy for exposure to bycatch, and to inform avoidance and mitigation actions. Using comprehensive records of commercial demersal longline and trap fishing and survey information for albatrosses (black-footed albatross Phoebastria nigripes, Laysan albatross P. immutabilis, short-tailed albatross P. albatrus), the extent of spatial potential interaction was estimated in Canada’s Pacific coast waters and examined across breeding and non-breeding seasons. The distributions of albatrosses and longline and trap fisheries were found to substantially overlap, with potential interaction hotspots concentrated along the continental shelf break. Trap fisheries reported 1 albatross bycatch incident, suggesting that these fisheries are responsible for negligible albatross mortalities. In contrast, >80% of recorded albatross bycatch incidents occurred within 10 km of albatross-longline fisheries hotspot locations, providing evidence that longline-albatross potential interaction hotspots represent actual areas of elevated bycatch mortality risk. Indicative of potential conservation concern, 60% of short-tailed albatross sightings occurred within 10 km, and 93% within 30 km, of longline-albatross potential interaction hotspots. By contributing knowledge regarding albatross-fisheries interactions, in addition to undertaking the first evaluation of albatross-fisheries hotspots with recorded bycatch incidents on Canada’s Pacific coast, this study represents a step towards enhancing albatross conservation through bycatch avoidance and mitigation.
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Benaka, Lee R., Andrea N. Chan, Steven J. Kennelly, and Noelle A. Olsen. "Using a tier classification system to evaluate the quality of bycatch estimates from fisheries." Reviews in Fish Biology and Fisheries 31, no. 3 (July 12, 2021): 737–52. http://dx.doi.org/10.1007/s11160-021-09670-y.
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AbstractBycatch continues to be a challenge to sustainable fisheries management (The term “bycatch” in this paper covers discards and does not include retained incidental catch). Bycatch estimates can inform stock status determinations by improving understanding of fishing mortality, and help managers monitor the effectiveness of regulations. Assessments of the quality of bycatch estimation programs and procedures are necessary to evaluate the precision and limitations of their results over time. NOAA Fisheries experts used a “Tier Classification System” (TCS) to compare the quality of fish bycatch data and estimation methods for U.S. commercial fisheries in 2005 and 2015. The TCS included criteria related to data adequacy and analytical approaches. A comparison of U.S. fishery tier scores demonstrated that most fisheries were classified into higher tiers in 2015 compared to 2005 due to factors including improved sampling design. In addition, this comparison identified region-specific trends (e.g., mostly improvements occurred for Alaska fisheries with more mixed results for Greater Atlantic fisheries). The improvements in bycatch data quality and estimation methods in the United States are a result of financial investments in observer programs by NOAA Fisheries and industry partners, as well as effective conservation measures implemented by regional fishery management councils and NOAA Fisheries. The TCS was also used to assess bycatch data and estimation methods in all of Australia’s fishery jurisdictions for the decade 2010–19, illustrating the international applicability of the method. Overall, Australian state fisheries scored lower than federally managed fisheries in both the United States and Australia, reflecting the fact that the latter fisheries tend to be larger (and more valuable) than those in state jurisdictions, with a larger investment in observer programs. A comparison of tier scores and estimates of discards by fishery may provide a useful input for decision-making processes regarding allocation of resources to improve bycatch monitoring.
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Lakenarine, Rovindra, Netra Chhetri, Neha Chhetri, and Jesse Senko. "Characterization of small-scale net fisheries off the coast of Guyana." PLOS ONE 19, no. 6 (June 28, 2024): e0306332. http://dx.doi.org/10.1371/journal.pone.0306332.
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Fish stocks have declined rapidly over the past half-century due to the increased demand for seafood and unsustainable fishing practices. The incidental capture of non-target species (bycatch) is a pervasive issue in fisheries management and has led to population declines in non-target species worldwide. The fisheries sector in Guyana currently supports the livelihoods of over 10,000 Guyanese and contributes approximately 2% to the country’s GDP. Bycatch is believed to be a major threat to Guyana’s marine fisheries, especially the small-scale sector, due to a lack of management infrastructure and limited data and monitoring. Here, we assessed bycatch in Guyana’s artisanal gillnet and Chinese seine fisheries through vessel observations and semi-structured interviews with local fishers. Most of the discarded species documented had no commercial importance to the fisheries in Guyana. Although no statistical difference was observed among the bycatch rates in the gillnet and Chinese seine fisheries, the latter generally had more discarded individuals, most of which were juveniles. The Shannon-Weiner diversity index showed a greater diversity of bycatch species in the gillnet fisheries compared to the Chinese seine. Jaccard’s similarity index indicated a low similarity among the gear types. Even though most fishers were aware of bycatch, they did not view it as a major issue and were not interested in reducing their discards. We recommend a collaborative approach in exploring solutions to ensure the ecological and socioeconomic sustainability of the fisheries sector.
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LEBRETON, JEAN-DOMINIQUE, and SOPHIE VÉRAN. "Direct evidence of the impact of longline fishery on mortality in the Black-footed Albatross Phoebastria nigripes." Bird Conservation International 23, no. 1 (July 4, 2012): 25–35. http://dx.doi.org/10.1017/s0959270912000299.
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SummaryThe incidental bycatch of seabirds in longline fisheries is one of the most striking examples of diffuse and incidental impact of human activities on vertebrate species. While there are various types of evidence of a strong impact of longline fisheries on seabirds, in particular albatrosses, the incidental bycatch mortality has never been directly linked to estimates of bycatch derived from on-board surveys. We develop a capture-recapture analysis which relates the annual probability of survival in the Black-Footed Albatross to the estimated absolute bycatch. By converting the absolute bycatch into an estimate relative to population size and using the theory of exploited populations, we show that survival probability decreases linearly with bycatch, and that the bycatch is underestimated by at least 50%, confirming suspicions based on reviews of the bycatch survey procedures, and raising further concerns about the impact of longline fisheries on seabirds.
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Elnes, Jonas O., André Moan, Kjell T. Nilssen, L. Asbjørn Vøllestad, and Arne Bjørge. "Temporal and Spatial Distribution of Harbor Seal (Phoca vitulina) Risk of Entanglement in Gillnets Along the Norwegian Coast." Aquatic Mammals 49, no. 6 (November 15, 2023): 508–18. http://dx.doi.org/10.1578/am.49.6.2023.508.
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Incidental capture of non-target species by fisheries, also referred to as bycatch, is a major concern for the management of marine megafauna species. In Norway, it has been estimated that 555 harbor seals (Phoca vitulina) get entangled and drown in gillnets every year. The majority of these bycatch events occur in large-mesh gillnet fisheries targeting cod (Gadus morhua) and monkfish (Lophius piscatorius). Young-of-the-year individuals represent the largest proportion of bycaught harbor seals. To increase our understanding of harbor seal bycatch events along the Norwegian coast, times and areas of potential bycatch risk were identified. Seasonal variation in the at-sea distribution of harbor seals was simulated based on movement from their molting site to predicted at-sea locations. Relative age-specific bycatch abundances were used to weigh the different seasons (times of the year) based on harbor seal age. The overlap in the distribution of harbor seals and the documented distribution of fishing effort was then used to estimate the relative bycatch risks between harbor seals and fisheries in defined Statistical Sea Locations (SSLs) in each of the four seasons. The method used here provides a general framework for understanding temporal and spatial interaction between harbor seals and coastal gillnet fisheries. The times and areas of high interaction risk that were identified can be used in management practices to increase our understanding of bycatch events, and to ultimately reduce unwanted bycatch of harbor seals in coastal fisheries along the Norwegian coast.
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Sims, Michelle, Tara Cox, and Rebecca Lewison. "MODELING SPATIAL PATTERNS IN FISHERIES BYCATCH: IMPROVING BYCATCH MAPS TO AID FISHERIES MANAGEMENT." Ecological Applications 18, no. 3 (April 2008): 649–61. http://dx.doi.org/10.1890/07-0685.1.
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Mauliddin, Muhamad, Romie Jhonnerie, and Nofrizal Nofrizal. "Pengurangan Hasil Tangkapan Pada Alat Tangkap Togok dengan Menggunakan BRD (Bycatch Reduction Device) Tipe Rope BRD di Kuala Tungkal, Provinsi Jambi." Dinamika Lingkungan Indonesia 9, no. 2 (July 31, 2022): 113. http://dx.doi.org/10.31258/dli.9.2.p.113-117.
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Togok is a fishing gear in the form of a conical net body whose arms are on two poles and the success of catching it relies on currents, togok fishing gear is used to catch Rebon shrimp (Acetes japonicas) but in its operation, many catches are found bycatch. The high bycatch will have an impact on capture sustainable fisheries, one of the efforts to reduce bycatch is by using BRD (Bycatch Reduction Devices), the use of BRD has been widely carried out on trawl fishing gear but on togok fishing gear, it has never been done. This study aimed for knowing the reduction in catches of main catch, bycatch, and discard the togok fishing gear that has been installed with rope BRD and knows the reduction in catches of shrimp and fish species. This study uses experimental fishing, namely by carrying out direct fishing operations with local fishermen for 20 days of catch. The reduction of togok catch using BRD type rope BRD in the main catch is 8.4%, in bycatch is 11.8% and discard is 17, 1% and the reduction in catch of shrimp species ranged from 8,4% - 13,5% and reduction in catch of fish species ranged from 10,9% - 22,6%.
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Kakai, Timothy M. "Assessing the effectiveness of LED lights for the reduction of sea turtle bycatch in an artisanal gillnet fishery - a case study from the north coast of Kenya." Western Indian Ocean Journal of Marine Science 18, no. 2 (November 8, 2019): 37–44. http://dx.doi.org/10.4314/wiojms.v18i2.4.
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Artisanal gillnet fisheries exist throughout the world’s oceans and have been responsible for high bycatch rates of sea turtles. Three sites on the north coast of Kenya, i.e. Watamu, Ngomeni, and Bwana Said, were studied with the overall objective of assessing the effectiveness of LED lights in the reduction of sea turtle bycatch in the bottom-set gillnet fishery. A total of 10 boats with pairs of control and illuminated nets were deployed during the study, with 56 turtles caught in control nets, while 30 were caught in illuminated nets. The mean catch per unit effort (CPUE) of target species was similar for both control and illuminated nets. In contrast, the mean CPUE of sea turtles was reduced by 64.3% in illuminated nets. This statistically significant decrease (p < 0.04) in sea turtle catch rate suggests that net illumination could be an effective conservation tool. Some useful data on fish catch rates with and without LED lights were also obtained, and interviews with fishermen suggested that they believe that the lights are effective at reducing marine turtle bycatch in their gill nets when set at night. The issues associated with implementing the use of LED lights included increased net handling times, equipment costs, and limited awareness among fishermen regarding the effectiveness of this technology. These challenges need the support of other stakeholders, especially national government, so as to implement this strategy of reducing turtle bycatch more widely.
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Punt, André E., Paula Moreno, John R. Brandon, and Michael A. Mathews. "Conserving and recovering vulnerable marine species: a comprehensive evaluation of the US approach for marine mammals." ICES Journal of Marine Science 75, no. 5 (June 11, 2018): 1813–31. http://dx.doi.org/10.1093/icesjms/fsy049.
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Abstract Human-caused mortality due primarily to bycatch in fisheries is considered a major threat to some long-lived, slow-growing, and otherwise vulnerable marine species. Under many jurisdictions these species are designated as “protected”, and fisheries are subject to a management system that includes monitoring and assessment of bycatch impacts relative to management objectives. The US management system for marine mammals is one of the most sophisticated in the world, with a limit on human-caused mortality computed using the potential biological removal (PBR), formula. Fisheries are categorized according to their impact relative to PBR, and take reduction teams established to develop take reduction plans (TRPs) when bycatch exceeds PBR. The default values of the parameters of the PBR formula were selected in the late 1990s using management strategy evaluation (MSE), but the system, in particular the classification of fisheries, has yet to be evaluated in its entirety. A MSE framework is developed that includes the PBR formula, as well as the processes for evaluating whether a stock is “strategic”, assigning fisheries to categories, and implementing TRPs. The level of error associated with fisheries classification was found not to impact the ability to achieve the conservation objective established for a stock under the US Marine Mammal Protection Act (i.e. maintain or recover the stock to/at optimum sustainable population). However, this ability is highly dependent on the life history and absolute abundance of the species being managed, as well as on the premise that bycatch is reduced if bycatch is estimated to exceed the PBR. The probability of correctly classifying fisheries depends on both the coefficient of variations (CVs) of the estimates of bycatch and the marine mammal stock’s abundance because classification depends on the ratio of the estimate of bycatch by fishery-type to the stock’s PBR, and the precision of the former depends on the bycatch CV and the latter on the abundance estimate CV. Moreover, the probability of correctly classifying a fishery decreases for smaller populations, particularly when a fishery has low to moderate impact.
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Cleasby, IR, LJ Wilson, R. Crawford, E. Owen, Y. Rouxel, and M. Bolton. "Assessing bycatch risk from gillnet fisheries for three species of diving seabird in the UK." Marine Ecology Progress Series 684 (February 17, 2022): 157–79. http://dx.doi.org/10.3354/meps13944.
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Incidental mortality (bycatch) in fisheries represents a threat to marine vertebrates. Research has predominantly focussed on bycatch in longline fisheries, but bycatch from gillnet fisheries is of increasing concern. To address this concern, we combined comprehensive biologging data sets and multiple sources of fishing effort data to assess the spatial overlap of 3 diving seabird species during the breeding season (common guillemot Uria aalge, razorbill Alca torda and European shag Phalacrocorax aristotelis) with UK gillnet fisheries. Species distribution models based on birds’ diving behaviour identified areas of elevated bycatch risk where high levels of diving activity and fishing effort coincided. In addition, we identified times of day and water depths where diving activity, and hence bycatch risk, may be concentrated. Bycatch risk hotspots for all 3 species were identified along the north-east coast of England. Risk hotspots were also identified along the Pembrokeshire coast for both auk species and along the Cornish coast for shag. Lack of fishing effort data for smaller vessels made it difficult to assess seabird-fishery overlap in Scottish waters. Across species, diving activity was lower at night. For razorbill and guillemot, dive depth tended to increase at sunrise and decrease after sunset. For shag, dive depth showed no diel pattern but was associated with water depth. Our findings should assist in targeting spatio-temporal measures and designing deterrent devices to reduce bycatch. However, scarcity of data on the behaviour of gillnet fishers at comparable spatio-temporal resolution as seabird movement data remains a constraint to fully understanding seabird-fisheries interactions.
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Crowder, Larry B., and Steven A. Murawski. "Fisheries Bycatch: Implications for Management." Fisheries 23, no. 6 (June 1998): 8–17. http://dx.doi.org/10.1577/1548-8446(1998)023<0008:fbifm>2.0.co;2.
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Vignieri, Sacha. "Healthy fisheries can reduce bycatch." Science 359, no. 6381 (March 15, 2018): 1227.1–1227. http://dx.doi.org/10.1126/science.359.6381.1227-a.
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Hall, Martin, Eric Gilman, Hiroshi Minami, Takahisa Mituhasi, and Erin Carruthers. "Mitigating bycatch in tuna fisheries." Reviews in Fish Biology and Fisheries 27, no. 4 (June 2, 2017): 881–908. http://dx.doi.org/10.1007/s11160-017-9478-x.
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Scales, Kylie L., Elliott L. Hazen, Michael G. Jacox, Frederic Castruccio, Sara M. Maxwell, Rebecca L. Lewison, and Steven J. Bograd. "Fisheries bycatch risk to marine megafauna is intensified in Lagrangian coherent structures." Proceedings of the National Academy of Sciences 115, no. 28 (June 25, 2018): 7362–67. http://dx.doi.org/10.1073/pnas.1801270115.
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Incidental catch of nontarget species (bycatch) is a major barrier to ecological and economic sustainability in marine capture fisheries. Key to mitigating bycatch is an understanding of the habitat requirements of target and nontarget species and the influence of heterogeneity and variability in the dynamic marine environment. While patterns of overlap among marine capture fisheries and habitats of a taxonomically diverse range of marine vertebrates have been reported, a mechanistic understanding of the real-time physical drivers of bycatch events is lacking. Moving from describing patterns toward understanding processes, we apply a Lagrangian analysis to a high-resolution ocean model output to elucidate the fundamental mechanisms that drive fisheries interactions. We find that the likelihood of marine megafauna bycatch is intensified in attracting Lagrangian coherent structures associated with submesoscale and mesoscale filaments, fronts, and eddies. These results highlight how the real-time tracking of dynamic structures in the oceans can support fisheries sustainability and advance ecosystem-based management.
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Rahim, Nurul Hidayah Abdul, Azzakirat Abdul Raman, Azmi Marzuki Muda, Saifullah Arifin Jaaman*, and Xuelei Zhang. "Bycatch Estimates of Dugongs and Dolphins: Results from an Interview Survey of Fishermen in Brunei Bay, Malaysia." Borneo Journal of Marine Science and Aquaculture (BJoMSA) 7 (December 31, 2023): 30–54. http://dx.doi.org/10.51200/bjomsa.v7i.4192.
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Bycatch refers to the unintentional capture of non-targeted animals during fishing activities. Worldwide, bycatch poses a significant threat to marine mammal species. In the Southeast Asian region, information on bycatch is particularly scarce, and there is little indication that the issue is adequately addressed anywhere in the region. To address this knowledge gap, we conducted face-to-face interview surveys across fishing communities in the Malaysian side of the Brunei Bay. We collected two datasets of marine mammal bycatch incidences from two different groups of fishermen (N=90 of 356 reported dugong data, 0.3%, and N=62 of 146 reported dolphin data, 0.4%), to estimate the levels of mortalities of the marine mammals. More than four fifths (82.1%) of respondents reported that they have accidentally captured at least one marine mammal (25.0% dugong and 42.5% dolphin) throughout their lifetime as a fisherman, with the highest frequency of occurrence being reported by fishers using gillnets (53.5% and 38.7%, respectively). Our interview results suggest an annual bycatch of 0.22 (95% CI = 0.13 to 0.32) for dugongs and 0.65 (95% CI = 0.40 to 0.88) for dolphins in the Malaysian Brunei Bay. Findings from this study provides important data to guide fisheries resource managers in providing protection and conservation efforts the endangered marine mammal populations.
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Watson, John, Daniel Foster, Scoll Nichols, Arvlnd Shah, Elizabeth Scoll-oenlon, and James Nanc. "The Development of Bycatch Reduction Technology in the Southeastern United States Shrimp Fishery." Marine Technology Society Journal 33, no. 2 (January 1, 1999): 51–56. http://dx.doi.org/10.4031/mtsj.33.2.8.
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Shrimp trawl bycatch is a significant source of fishery induced mortality for managed species including red snapper (Lutjanus campechanus Poey), Spanish mackerel (Scomberomorus maculatus MitcheU), and weakfish (Cynoscion regalis Baloch, Schneider) in the southeastern United States. These species have been overfished and are under both state and federal management plans which include regulations mandating reduction of shrimp trawl bycatch mortality. In 1990 the U.S. Congress passed amendments to the Magnuson Fishery Conservation and Management Act (16 U.S.C. 1854) which called for a research program that included the design and evaluation of approaches for reducing shrimp trawl bycatch mortality. A strategic planning initiative addressing finfish bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries was developed by the Gulf and South Atlantic Fisheries Foundation through funding and guidance provided by the National Marine Fisheries Service. A cooperative research plan was developed in 1992 which included the identification, development, and evaluation of gear options for reducing bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries. Between 1990 and 1996 one hundred and forty five bycatch reduction conceptual gear designs contributed by fishers, net shops, gear technicians, and biologists were evaluated. Sixteen of these designs were tested on cooperative commercial shrimp vessels by observers under the southeast regional cooperative bycatch program. Analyses of data from commercial vessel testing indicates that two bycatch reduction designs have potential to significantly reduce shrimp trawl bycatch for weakfish and Spanish mackerel in the southeastern Atlantic and two designs have the potential to significantly reduce red snapper bycatch in the Gulf of Mexico. The fisheye and the extended funnel bycatch reduction devices have been mandated for use in the southeastern Atlantic shrimp fishery and the fisheye and Jones/Davis bycatch reduction devices have been mandated for use in the Gulf of Mexico shrimp trawl fishery.
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Mangel, Jeffrey C., John Wang, Joanna Alfaro-Shigueto, Sergio Pingo, Astrid Jimenez, Felipe Carvalho, Yonat Swimmer, and Brendan J. Godley. "Illuminating gillnets to save seabirds and the potential for multi-taxa bycatch mitigation." Royal Society Open Science 5, no. 7 (July 2018): 180254. http://dx.doi.org/10.1098/rsos.180254.
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Bycatch in net fisheries is recognized as a major source of mortality for many marine species, including seabirds. Few mitigation solutions, however, have been identified. We assessed the effectiveness of illuminating fishing nets with green light emitting diodes (LEDs) to reduce the incidental capture of seabirds. Experiments were conducted in the demersal, set gillnet fishery of Constante, Peru and compared 114 pairs of control and illuminated nets. We observed captures of a total of 45 guanay cormorants ( Phalacrocorax bougainvillii ), with 39 caught in control nets and six caught in illuminated nets. Seabird bycatch in terms of catch-per-unit-effort was significantly ( p < 0.05) higher in control nets than in illuminated nets, representing an 85.1% decline in the cormorant bycatch rate. This study, showing that net illumination reduces seabird bycatch and previous studies showing reductions in sea turtle bycatch without reducing target catch, indicates that net illumination can be an effective multi-taxa bycatch mitigation technique. This finding has broad implications for bycatch mitigation in net fisheries given LED technology's relatively low cost, the global ubiquity of net fisheries and the current paucity of bycatch mitigation solutions.
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Sitorus, Yuni Debora Prasicilia, Ida Ayu Astarini, and I. Made Antara. "Identification Of Bycatch Sharks In The India Ocean Based On DNA Barcoding In Conservation Effort." Journal of Marine and Aquatic Sciences 9, no. 2 (December 1, 2023): 162. http://dx.doi.org/10.24843/jmas.2023.v09.i02.p02.
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The most potential shark fishing area in Indonesia is the Indian Ocean. One of the fishing ports that has bycatch shark is Benoa Harbor. The purpose of this research is to identify species to determine the conservation status of bycatch shark species from body tissue samples caught in the Indian Ocean in conservation efforts. The research was conducted from January to March 2021 at Pangkalan Pengawasan Sumber Daya Kelautan dan Perikanan (PSDKP) of Benoa Harbor. This study uses an exploratory method with survey techniques. The data used in this study are primary data in the form of shark fin samples in the study area and secondary data in the form of locations where sharks are caught by fishermen based on the PSDKP database. The results showed that sharks bycatch from body tissue samples caught in the Indian Ocean based on morphological identification and DNA barcoding techniques were Prionace glauca, Isurus paucus, Sphyrna zygaena, Isurus oxyrinchus, Alopias superciliosus and Carcharhinus longimanus. Bycatch sharks from body tissue samples caught in the Indian Ocean based on morphological identification and DNA barcoding techniques have close phylogenetic relationships with the Carcharhinidae, Sphyrnidae, Alopiidae and Lamnidae families. Bycatched shark from body tissue samples caught in the Indian Ocean based on morphological identification and DNA barcoding techniques has a conservation status, near threatened for Prionace glauca species, vulnerable for Sphyrna zygaena species and Alopias superciliosus species, endangered for Isurus paucus species and Isurus oxyrinchus species, critically endangered for Carcharhinus longimanus species.
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Shirakihara, Miki, and Kunio Shirakihara. "Bycatch of the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in gillnet fisheries off Amakusa-Shimoshima Island, Japan." J. Cetacean Res. Manage. 12, no. 3 (February 8, 2023): 345–51. http://dx.doi.org/10.47536/jcrm.v12i3.566.
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A year-round resident population of the Indo-Pacific bottlenose dolphin (Tursiops aduncus) inhabits the waters off Amakusa-Shimoshima Island (32°25′N, 130°05´E), in Japan. The effect of bycatch in gillnet fisheries on the Amakusa population was examined. Population size in 2007 and 2008 was estimated at 230 individuals (CV = 2.5%) and 216 individuals (CV = 2.1%), respectively, based on a mark-recapture technique. The magnitude of bycatch was evaluated by analysing interview surveys (263 gillnetters) during these two years. Minimum numbers of dolphin bycatch were 12 individuals in 2007 and 14 individuals in 2008. Most of the dolphins, which were captured by bottom-set gillnets, were considered to be Indo-Pacific bottlenose dolphins for the following reasons: (1) two individuals were identified based on DNA analysis; (2) only Tursiops sp. and finless porpoises were found in the sighting survey by ferry boats, and fishermen can distinguish between the two; and (3) the seasonal and spatial distribution of bycatch corresponded well to habitat use patterns of the Amakusa population. If the US potential biological removal (PBR) approach is used it estimates two individuals per year, which is much lower than the minimum bycatch numbers of 12–14 individuals per year (5.2–6.5% of abundance estimates). Reducing bycatch mortality caused by bottom-set gillnets is essential for the effective conservation of Indo-Pacific bottlenose dolphins in Amakusa, Japan.
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Lozano, M., J. Baro, T. García, A. Frias, A. Rey, and J. C. Báez. "Loggerhead sea turtle bycatch data in artisanal fisheries within a marine protected area: fishermen surveys versus scientific observations." Animal Biodiversity and Conservation 34, no. 1 (2011): 31–34. http://dx.doi.org/10.32800/abc.2011.34.0031.
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Loggerhead sea turtles can be incidentally captured by artisanal gears but information about the impact of this fishing is inconsistent and scarce. Recent studies have observed that the bycatch, or incidental catch rate, in fishermen surveys is irregular. The aim of this study was to compare direct data (onboard observers) concerning the incidental catch of loggerhead sea turtles by the artisanal vessels versus data from fishermen surveys. The study area was the Cabo de Gata-Níjar marine protected area, situated in the western Mediterranean (southeast of the Iberian peninsula). We observed two loggerhead turtles that were incidentally caught in a total of 165 fishing operations. According to fishermen surveys, a total of nine loggerheads were incidentally caught in 861 fishing operations. The differences between the loggerhead sea turtle bycatch reported by fishermen surveys and scientific observations versus random distribution (x2 = 0.3146, P = 0.575, df = 1) were not significant. We conclude that the surveys are useful but that findings should be interpreted with caution.
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Werner, Timothy, Scott Kraus, Andrew Read, and Erika Zollett. "Fishing Techniques to Reduce the Bycatch of Threatened Marine Animals." Marine Technology Society Journal 40, no. 3 (September 1, 2006): 50–68. http://dx.doi.org/10.4031/002533206787353204.
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Unintended injuries and fatalities to non-target marine species—a major component of “bycatch”—is one of the principal threats to the survival of many endangered marine populations and species. This paper describes both proposed and existing fishing techniques for reducing non-target species bycatch, and reviews their focus across different fisheries and wildlife groups. The intent of this inventory was to gain a better understanding of the range of techniques available and to highlight priorities for research and development. In all, 55 techniques were identified, with the majority directed at reducing bycatch in longline fisheries, and intended to benefit primarily seabirds, sea turtles, and small mammals. Bycatch reduction is a dynamic field with many examples of effective techniques, though some underserved fisheries and wildlife groups should receive more attention.
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Le Bot, Tangi, Amélie Lescroël, and David Grémillet. "A toolkit to study seabird–fishery interactions." ICES Journal of Marine Science 75, no. 5 (April 2, 2018): 1513–25. http://dx.doi.org/10.1093/icesjms/fsy038.
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Abstract Seabirds and fisheries have been interacting from ancient times, sometimes with mutual benefits: Seabirds provided fishermen with visual cues of fish aggregations, and also fed upon food subsids generated by fishing activities. Yet fisheries and seabirds may also compete for the same resources, and their interactions can lead to additional seabird mortality through accidental bycatch and diminishing fishing efficiency, threatening vulnerable seabird populations. Understanding these complex relationships is essential for conservation strategies, also because it could enhance and ease discussion between stakeholders, towards a common vision for marine ecosystem management. As an aid in this process, we reviewed 510 scientific publications dedicated to seabirds–fisheries interactions, and compiled a methodological toolkit. Methods employed therein serve four main purposes: (i) Implementing distribution overlap analyses, to highlight areas of encounter between seabirds and fisheries (ii) Analysing movement and behavioural patterns using finer-scale information, to characterize interaction types (iii) Investigating individual-scale feeding ecology, to assess fisheries impacts at the scale of bird populations, and (iv) Quantifying the impacts of seabird–fishery interactions on seabird demography and population trends. This latter step allows determining thresholds and tipping points with respect to ecological sustainability. Overall, we stress that forthcoming studies should integrate those multiple approaches, in order to identify and promote best practices towards ecosystem-based fisheries management and ecologically sound marine spatial planning.
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Breivik, Olav Nikolai, Geir Storvik, and Kjell Nedreaas. "Latent Gaussian models to decide on spatial closures for bycatch management in the Barents Sea shrimp fishery." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 8 (August 2016): 1271–80. http://dx.doi.org/10.1139/cjfas-2015-0322.
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In the Barents Sea and adjacent water, fishing grounds are closed for shrimp fishing by the Norwegian Directorate of Fisheries Monitoring and Surveillance Service (MSS) if the expected number of juvenile fish caught are predicted to exceed a certain limit per kilogram shrimp (Pandalus borealis). Today, a simple ratio estimator, which does not fully utilize all data available, is in use. In this paper, we construct a Bayesian hierarchical spatiotemporal model for improved prediction of the bycatch ratio in the Barents Sea shrimp fishery. More predictable bycatch will be an advantage for the MSS because of more correct decisions and better resource allocation and also for the fishermen because of more predictable fishing grounds. The model assumes that the occurrence of shrimp and juvenile Atlantic cod (Gadus morhua) can be modeled by linked regression models containing several covariates (including 0-group abundance estimates) and random effects modeled as Gaussian fields. Integrated nested Laplace approximations is applied for fast calculation. The method is applied to prediction of the bycatch ratio for Atlantic cod.
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Hamid, Abdul, and Syamsul Kamri. "KEANEKARAGAMAN JENIS IKAN HASIL TANGKAPAN SAMPINGAN (BYCATCH) PERIKANAN RAJUNGAN DI TELUK LASONGKO DAN KENDARI SULAWESI TENGGARA." Marine Fisheries : Journal of Marine Fisheries Technology and Management 10, no. 2 (November 11, 2019): 215–24. http://dx.doi.org/10.29244/jmf.v10i2.30855.
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Information regarding the diversity of bycatch from blue swimming crab fishing operations is important in ecosystem-based management and assessment for Marine Stewardship Council (MSC) certification of crab fisheries in Southeast Sulawesi and Indonesia. However, data limitation becomes major challenges. This study aims to specify the types of bycatch caught from blue swimming crab fishing in Lasongko and Kendari Bay Southeast Sulawesi. This research was conducted in March to September 2019. Data was collected from trap and bottom gillnet fishing by using a purposive sampling method on a monthly basis. Bycatch was categorized into two groups, namely economically valuable and discarded, according to the local fishers’ perception. Information was presented both spatially and temporally. The results show that bycatch consists of 66 species including 41 economically valuable and 26 discarded species. Indices of diversity, evenness and dominance of fish were also discussed to describe the ecological conditions. Accordingly, this bycatch composition is able to support the management and assessment of MSC certification of crab fisheries in Southeast Sulawesi.
Keywords: bycatch, fish diversity, blue swimming crab fisheries, Southeast Sulawesi.
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Zhou, Can, and Baochao Liao. "Assessing the Uncertainty of Total Seabird Bycatch Estimates Synthesized from Multiple Sources with a Scenario Analysis from the Western and Central Pacific." Birds 3, no. 3 (August 10, 2022): 260–76. http://dx.doi.org/10.3390/birds3030017.
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Each year, billions of seabirds undertake migrations, connecting remote regions of the world, potentially synchronizing population fluctuations among distant areas. This connectedness has implications for the uncertainty calculations of the total seabird bycatch estimate at a regional/global scale. Globally, fisheries bycatch poses a major problem in fishery management, and estimating the uncertainty associated with a regional/global seabird bycatch estimate is important because it characterizes the accuracy and reliability of the fisheries’ impact on the seabird populations. In this study, we evaluate different assumptions underlying the estimation of the variability of the total seabird bycatch at a regional/global scale based on local assessment reports. In addition to theoretical analysis, we also simulate multiple spatially distant separately managed areas with relatively low levels of observer coverage, based on bycatch data from the Western and Central Pacific Fisheries Commission convention area. The results show that assuming a completely synchronized variation produced the most conservative uncertainty estimate and it also missed an opportunity to improve the precision. Simplified correlation structures also failed to capture the complex dynamics of bycatch rates among spatially distant areas. It is recommended to empirically estimate the correlation of bycatch rates between each pair of sources based on bycatch rate time series.
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Runnebaum, J., KR Tanaka, L. Guan, J. Cao, L. O’Brien, and Y. Chen. "Predicting bycatch hotspots based on suitable habitat derived from fishery-independent data." Marine Ecology Progress Series 641 (May 7, 2020): 159–75. http://dx.doi.org/10.3354/meps13302.
Full textAbstract:
Bycatch remains a global problem in managing sustainable fisheries. A critical aspect of management is understanding the timing and spatial extent of bycatch. Fisheries management often relies on observed bycatch data, which are not always available due to a lack of reporting or observer coverage. Alternatively, analyzing the overlap in suitable habitat for the target and non-target species can provide a spatial management tool to understand where bycatch interactions are likely to occur. Potential bycatch hotspots based on suitable habitat were predicted for cusk Brosme brosme incidentally caught in the Gulf of Maine American lobster Homarus americanus fishery. Data from multiple fisheries-independent surveys were combined in a delta-generalized linear mixed model to generate spatially explicit density estimates for use in an independent habitat suitability index. The habitat suitability indices for American lobster and cusk were then compared to predict potential bycatch hotspot locations. Suitable habitat for American lobster has increased between 1980 and 2013 while suitable habitat for cusk decreased throughout most of the Gulf of Maine, except for Georges Basin and the Great South Channel. The proportion of overlap in suitable habitat varied interannually but decreased slightly in the spring and remained relatively stable in the fall over the time series. As Gulf of Maine temperatures continue to increase, the interactions between American lobster and cusk are predicted to decline as cusk habitat continues to constrict. This framework can contribute to fisheries managers’ understanding of changes in habitat overlap as climate conditions continue to change and alter where bycatch interactions could occur.
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Jubinville, I., E. Lawler, S. Tattrie, NL Shackell, J. Mills Flemming, and B. Worm. "Distributions of threatened skates and commercial fisheries inform conservation hotspots." Marine Ecology Progress Series 679 (November 25, 2021): 1–18. http://dx.doi.org/10.3354/meps13938.
Full textAbstract:
Bycatch in commercial fisheries is a pressing conservation concern and has spurred global interest in adopting ecosystem-based management practices. To address such concerns, a thorough understanding of spatiotemporal relationships among bycatch species, their environment and fisheries is required. Here we used a generalized linear mixed model framework incorporating spatiotemporal random effects to model abundance patterns for 3 skate species caught as bycatch in commercial fisheries (thorny skate Amblyraja radiata, winter skate Leucoraja ocellata and smooth skate Malacoraja senta), as well as 10 target species on the Scotian Shelf, NW Atlantic. Spatiotemporal estimates of relative abundance for at-risk skates within the years 2005-2015 were modelled from research trawl survey data and overlaid with those for target species to identify hotspots of bycatch risk. In addition, abundance estimates for at-risk skates within the years 1975-1985, a period of higher stock abundance, were used to identify areas of previously important habitat. Historically, skate species densely occupied areas near Sable Island and Banquereau Banks, Georges Bank and the Bay of Fundy. Bycatch hotspots between at-risk skates and commercial targets were identified in regions across the Scotian Shelf. These hotspots were independently validated by predicting species presence from at-sea observer data that monitor skate bycatch directly. We discuss spatial relationships between target and bycatch species, highlighting limitations of at-sea observer programmes that this method helps to address. This framework can be applied more broadly to inform ecosystem management and priority areas for conservation or fisheries regulation.
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GANDINI, PATRICIA, and ESTEBAN FRERE. "The economic cost of seabird bycatch in Argentinean longline fisheries." Bird Conservation International 22, no. 1 (September 26, 2011): 59–65. http://dx.doi.org/10.1017/s0959270911000219.
Full textAbstract:
SummarySeabird mortality in longline fisheries is believed to be an important cause of the reductions in many seabird populations worldwide, and results in reduced fishing efficiency and economic losses for fishing companies. We estimated the economic cost of not using seabird bycatch deterrents in Argentinean longline fisheries, with the intention of encouraging adoption of mitigation measures in those fisheries. We conducted the study in the Argentine ling Genypterus blacodes and Patagonian toothfish Dissostichus eleginoides fisheries from 2001 to 2006 on three fishing vessels. Data on the incidence of seabird bycatch were collected by seabird observers specially trained in seabird identification and data on the catch rates of target species, cost of bait and fish were provided by the fishing company, supervised by Federal Inspectors from the Provincial Fisheries Agency. To estimate the bait loss, we set lines both with and without the use of deterrents (streamer lines, night setting and strategic discharge of offal) in both fisheries. Seabird bycatch varies temporally and geographically, so to estimate economic losses using deterrents in each fishery, we used different bycatch rates/1000 hooks registered for different periods and fishing areas. Bycatch rates in the absence of deterrents were two birds/1000 hooks and 1.53 birds/1000 hooks for the Patagonian toothfish and ling fisheries, respectively. These rates equate to the loss of more than 1.5 and 2 million dollars over a 10 year period for each fishery. When estimations are made with lower mortality rates, economic losses declined abruptly and were in the order of hundreds of dollars/fishing trip, for the same period of time. Results show that using deterrents, long term profits for the fishing company increase at a considerably high rate (the decrease in monetary loss is an order of magnitude), and the mortality of seabirds decreases by the same proportion (CPUE of seabirds decreases from tens of thousands to a few hundred). In these fisheries, the use of mitigation measures that reduce bait loss and seabird mortality represents a win-win situation with benefits to conservation and fishing companies.
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Nofrizal, Nofrizal, Afni Afriani, Deni Efizon, and Romie Jhonnerie. "Percentage of the bycatch and discard composition in artisanal bottom trap fisheries." Depik 11, no. 2 (July 8, 2022): 139–47. http://dx.doi.org/10.13170/depik.11.2.26106.
Full textAbstract:
Data on bycatch in the fishing effort required to manage fisheries resources. Unfortunately, the data on small-scale and traditional fisheries is still lacking. It makes it challenging to make fishing policies and regulations. Survey activities and experimental fishing were conducted to determine and analyze the composition of the main catch, bycatch and discarded by the local fisher's bottom traps in Sibolga, North Sumatra, Indonesia. Five units of the trap with a size of 150 cm x 100 cm x 50 cm (length x width x height) were used to collect fish data. These five trap units operated in the fishing ground, where local fishers usually operate their fishing gear. The fishing operation carried out within 1 mile of the coastline with water depths ranging from 7-10 meters. The duration of trap setting around 5-7 days for each fishing operation. A motorboat operated with a weight of 5.8 GT. The results showed that the total bottom trap catch consisted of 329 individuals with a total weight of 151.4 kg and 12 demersal fish species. The main catch was 148 individuals (88.9 kg), or 44.7% of the total catch during the experiment i.e. Chepalapholis urodeta, Ephinephelus areolatus, Epinephelus chlorostigma, Plectropomus leopardus, Ephinepelus coioides, Lates calcarifer, Lutjanus malabaricus, and Lutjanus erytropterus. The bycatch was 151 individuals (57.1 kg) or 46.1% i.e. Lethrinus obsoletus, Lutjanus ehrenbergii, Acanthurus auranticavus, Platax teira, Nemipterus japonicus, Scarus rivulatus, Lutjanus johnii, Siganus canaliculatus, Caesio cuning, and Taeniura lymma.While the discarded catch amounted to 30 individuals (5.4 kg) or 9.2% i.e. Naso brevirostris, Diodon holocanthus, and Diadema setosum. The bycatch utilization obtained by fishers was 83.4%, and the unutilized was 16.6%. The percentage of fish sizes worthy for consumption was 135 individuals (74.6%), and the size unworthy for consumption was 46 individuals (25.4%).Keywords:Fishing groundFishing gear Fishing operation Main catchTrap