Journal articles: 'Seabird by-catch'

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Favero, M., and J. P. Seco Pon. "Challenges in seabird by-catch mitigation." Animal Conservation 17, no. 6 (November 27, 2014): 532–33. http://dx.doi.org/10.1111/acv.12180.

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Boyd, C. "Minimizing seabird by-catch in industrial fisheries." Animal Conservation 17, no. 6 (December 2014): 530–31. http://dx.doi.org/10.1111/acv.12179.

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Robertson, Graham. "The culture and practice of longline tuna fishing: implications for seabird by-catch mitigation." Bird Conservation International 8, no. 3 (September 1998): 211–21. http://dx.doi.org/10.1017/s095927090000188x.

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SummaryThe development of practical approaches to seabird by-catch reduction in longline tuna fisheries is dependent upon knowledge of fishing practices and the cultural and vocational nuances of fishermen. This overview, drawn from information gathered on Japanese tuna vessels in Australian waters, describes the Japanese method of tuna longlining and lists possible reasons for the reluctance shown by tuna fishermen in the adoption of measures to reduce the incidental take of seabirds. While the focus is on Japan there are reasons to believe that tuna fishing for long periods on the high seas is a culture of its own that transcends nationalities. The acceptance of change in fishing cultures, unless imposed by economic necessity or direct government policy, is slow. The overview also makes some suggestions for future efforts to reduce seabird deaths in longline tuna fisheries.

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Norden, W. S., and J. P. Pierre. "Exploiting sensory ecology to reduce seabird by-catch." Emu - Austral Ornithology 107, no. 1 (March 2007): 38–43. http://dx.doi.org/10.1071/mu06050.

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Ogi, Haruo. "International and National Problems in Fisheries Seabird By-Catch." Journal of Disaster Research 3, no. 3 (June 1, 2008): 187–95. http://dx.doi.org/10.20965/jdr.2008.p0187.

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Large-scale international fisheries have seen many developments, including the adoption of 200-mile fishing limits by many countries, including Japan, between 1976 and 1977. On the North Pacific high seas, the use of neon flying squid and large-mesh driftnets is expanding rapidly. The many kinds and large numbers of nontargeted species caught in such driftnets, however, influenced world public opinion and the United Nations to prohibit driftnet fishing on the high seas in 1991. The investigation on the consequences of such driftnets have been often failed to be conducted in Japan, because Japan’s fisheries have been downsized. Japan’s fishing industry has not addressed this problem appropriately, even though the authorities have recommended that fishing fleets minimize by-catch. Japan has no legislation designating sea surface conservation for sealife, and fisheries by-catch have dramatically reduced the number of breeding seabirds in isolated habitats. The Japanese murrelet (Synthliboramphus wumizusume) of Miyazaki Prefecture and the common murre (Uria aalge) and the tufted puffin (Lunda cirrhata) of Hokkaido face a serious situation. The number of the spectacled guillemot (Cepphus carbo) living along Tohoku-Hokkaido coast has rapidly decreased due to by-catch fishing. Russia has legislation designating breeding places for seabirds and animals and designating surroundings as conservation areas. The Northern Territory adjoining Hokkaido thus has extremely diverse sea species. Japan has no corresponding legislation to succeed the Russian conservation legislation if Russia should return the Northern Territories to Japan.

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Bull, Leigh S. "New mitigation measures reducing seabird by-catch in trawl fisheries." Fish and Fisheries 10, no. 4 (December 2009): 408–27. http://dx.doi.org/10.1111/j.1467-2979.2009.00327.x.

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Durán Muñoz, P., F. J. Murillo, M. Sayago-Gil, A. Serrano, M. Laporta, I. Otero, and C. Gómez. "Effects of deep-sea bottom longlining on the Hatton Bank fish communities and benthic ecosystem, north-east Atlantic." Journal of the Marine Biological Association of the United Kingdom 91, no. 4 (November 2, 2010): 939–52. http://dx.doi.org/10.1017/s0025315410001773.

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The effects of deep-sea bottom longlining on fish communities and the benthic ecosystem, as well as the interactions between fishing and seabirds, were studied based on data collected from a joint collaboration between the Spanish Institute of Oceanography and a longliner, carried out on the Hatton Bank area (north-east Atlantic) in 2008. A total of 38 longline sets were distributed mainly along the rugged bottom of the rocky outcrop at depths ranging from 750 to 1500 m. Deep-water sharks and lotids were predominant in the catches contributing respectively 80.4% and 13.1% in terms of weight. Deep-water sharks were predominant in the discards. By-catch of cold-water corals and small glass sponges occurred along the western flank of the Hatton Bank, while large hexactinellids were found along the eastern flank. Longlines fished the adult fraction of vulnerable deep-water sharks and lotids. High catches per unit effort values for these species were obtained in coral areas. A combination of seabird-scaring streamer lines and other measures of preventing seabird by-catch were used. Only one fulmar was captured and it survived. Data on distribution of marine litter and derelict deep-sea gillnets are also presented.

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Jahncke, Jaime, Elisa Goya, and Alex Guillen. "Seabird By-Catch in Small-Scale Longline Fisheries in Northern Peru." Waterbirds: The International Journal of Waterbird Biology 24, no. 1 (April 2001): 137. http://dx.doi.org/10.2307/1522255.

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Gilman, Eric, Nigel Brothers, and Donald R. Kobayashi. "Principles and approaches to abate seabird by-catch in longline fisheries." Fish and Fisheries 6, no. 1 (March 2005): 35–49. http://dx.doi.org/10.1111/j.1467-2679.2005.00175.x.

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10

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.

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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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Pon, Juan Pablo Seco, Sofía Copello, Ariel Moretinni, Hugo P. Lértora, Ignacio Bruno, Julián Bastida, Laura Mauco, and Marco Favero. "Seabird and marine-mammal attendance and by-catch in semi-industrial trawl fisheries in near-shore waters of northern Argentina." Marine and Freshwater Research 64, no. 3 (2013): 237. http://dx.doi.org/10.1071/mf12312.

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Seabird and marine-mammal attendance and by-catch in mid-water and bottom otter semi-industrial coastal pair-trawl fisheries were assessed for the first time in northern Argentina. Observers were placed onboard trawlers between autumn 2007 and autumn 2008. Fifteen marine top-predator species were associated with the vessels. The most abundant and frequent seabirds (trawl fisheries combined) were the kelp gull, Larus dominicanus (~70% of total birds and >96% occurrence), and the Olrog’s gull, L. atlanticus (~12% and >50%, respectively). Other seabird taxa such as Procellariiforms and Sphenisciforms, among others, were represented in very low numbers. The only mammal species recorded was the South American sea lion, Otaria flavescens (1% and 2%, respectively). Analysis of environmental and operational variability affecting the abundance of gulls indicated a significant increase in abundance with fishing depth, time of day, seasonality, wind intensity and wind direction. Incidental mortality of top predators was low and comprised only Magellanic penguins, Spheniscus magellanicus, in the mid-water gear. The results of the present study showed that the semi-industrial trawl fisheries operating in coastal waters in northern Argentina may a have a relatively minor impact on marine top-predator populations, at least in terms of incidental capture.

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Tuck, G. N., R. A. Phillips, C. Small, R. B. Thomson, N. L. Klaer, F. Taylor, R. M. Wanless, and H. Arrizabalaga. "An assessment of seabird–fishery interactions in the Atlantic Ocean." ICES Journal of Marine Science 68, no. 8 (September 1, 2011): 1628–37. http://dx.doi.org/10.1093/icesjms/fsr118.

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Abstract Tuck, G. N., Phillips, R. A., Small, C., Thomson, R. B., Klaer, N. L., Taylor, F., Wanless, R. M., and Arrizabalaga, H. 2011. An assessment of seabird–fishery interactions in the Atlantic Ocean. – ICES Journal of Marine Science, 68: 1628–1637. Currently, 17 of 22 albatross species are listed as Vulnerable, Endangered, or Critically endangered by the International Union for the Conservation of Nature (IUCN). Incidental mortality in fisheries is by far the most widespread cause of the population declines observed for these and other closely related species. In 2006, the International Commission for the Conservation of Atlantic Tunas (ICCAT) requested an assessment of the threat from their fisheries to all seabirds that breed or forage within their jurisdiction. Methods were developed to assess the potential consequences of fishing for more than 60 populations of seabird. The assessment framework involved the identification of at-risk populations, overlap analyses, estimation of total bycatch, and an evaluation of the impact of the bycatch on key selected populations for which there were sufficient data on bird distribution and demography. These were the wandering and black-browed albatrosses of South Georgia and the Atlantic yellow-nosed and Tristan albatrosses of Gough Island. Summary results from the seabird assessment are presented, revealing that ICCAT longline fisheries catch substantial numbers of seabirds, with potentially significant conservation implications. If this mortality is not reduced, the numbers of breeding birds in some populations will continue to decline, threatening their long-term viability.

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Phillips, R. A. "Requisite improvements to the estimation of seabird by-catch in pelagic longline fisheries." Animal Conservation 16, no. 2 (March 21, 2013): 157–58. http://dx.doi.org/10.1111/acv.12042.

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14

Løkkeborg, S. "Seabird by-catch and bait loss in long-lining using different setting methods." ICES Journal of Marine Science 55, no. 1 (February 1998): 145–49. http://dx.doi.org/10.1006/jmsc.1997.9997.

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15

KARRIS, G., J. FRIC, Z. KITSOU, J. KALFOPOULOU, S. GIOKAS, S. SFENTHOURAKIS, and K. POIRAZIDIS. "Does by-catch pose a threat for the conservation of seabird populations in the southern Ionian Sea (eastern Mediterranean)? A questionnaire based survey of local fisheries." Mediterranean Marine Science 14, no. 3 (September 12, 2013): 19. http://dx.doi.org/10.12681/mms.541.

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A significant number of studies worldwide have shown that incidental catches (by-catch) of seabirds in fishing gear might pose a considerable risk for the conservation of their populations. Nevertheless reliable data on by-catch rates of seabirds in European marine ecosystems are patchy and need to be improved. This study constitutes a first attempt at the evaluation of by-catch rates in the southern Ionian Sea. Data were obtained by distributing a specific questionnaire to the fishers of Zakynthos Island. 150 professional fishers (representing 90% of the local fishing fleet) participated in the research, and were interviewed during July-December 2010. The information collected showed that commercial longline and (to a lesser extent) gillnet fishery gears caused incidental catches mostly of Scopoli’s Shearwater and Mediterranean Shag. The temporal analysis of the incidental bird mortality showed that seabirds were more susceptible to be trapped in fishery gears set around sunrise during spring and summer whereas spatial analysis of by-catch data indicated variations in the number of seabirds caught in different fishery areas.

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Favero, Marco, Camilo Eduardo Khatchikian, Alejandro Arias, María Patricia Silva Rodriguez, Guillermo Cañete, and Rocío Mariano-Jelicich. "Estimates of seabird by-catch along the Patagonian Shelf by Argentine longline fishing vessels, 1999–2001." Bird Conservation International 13, no. 4 (November 20, 2003): 273–81. http://dx.doi.org/10.1017/s0959270903003204.

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The incidental mortality of albatrosses Diomedeidae and petrels Procellariidae by longline fishing vessels, has been assessed and analysed in several areas of the globe. We provide the first direct estimates of incidental mortality rates of albatrosses and petrels along the Argentine Shelf and shelf break. The estimated by-catch rate for the whole period analysed (1999-2001) was 0.04 birds/1,000 hooks, with a maximum of 0.20 birds/1,000 hooks observed in 1999. Annual captures averaged 1,160 birds; however, the large variation observed indicates that annual by-catch may be in the order of thousands, with around 10,000 seabirds being killed by longliners through the study period. Most of the captures were observed along the Patagonian shelf break. At least 12 bird species were incidentally taken, with Black-browed Albatrosses Thalassarche melanophris and White-chinned Petrels Procellaria aequinoctialis accounting for about 80% of total captures. The information provided in this study allowed the design and future implementation of mitigation measures and new survey methods onboard longliners operating in Atlantic waters on the Argentine shelf.

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Yeh, Y.-M., H.-W. Huang, K. S. Dietrich, and E. Melvin. "Estimates of seabird incidental catch by pelagic longline fisheries in the South Atlantic Ocean." Animal Conservation 16, no. 2 (September 7, 2012): 141–52. http://dx.doi.org/10.1111/j.1469-1795.2012.00588.x.

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Murray, T. E., J. A. Bartle, S. R. Kalish, and P. R. Taylor. "Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992." Bird Conservation International 3, no. 3 (September 1993): 181–210. http://dx.doi.org/10.1017/s0959270900000897.

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SummaryFishery observers recorded incidental capture of seabirds during 785 days on Japanese bluefin tuna longline vessels around New Zealand between April and August each year, 1988-1992. High numbers of albatrosses Diomedea spp. and petrels Procellaria spp. were caught on longline hooks during setting and drowned. Twelve seabird taxa were recorded, six of them breeding only in New Zealand. Most were breeding adults, except for Grey-headed and Black-browed Albatrosses. No bias in sex ratio was evident except for Grey Petrels, of which nearly all were female. Winter-breeding species were most often caught. Birds were not caught randomly, but in a highly aggregated fashion suggestive of complex behavioural interactions with the fishery. Most albatrosses were caught by day in the south whereas most petrels were caught by night north-east of New Zealand. Highest capture rates occurred at dawn and dusk off north-east New Zealand in June-August. Very large catches at specific sites contributed disproportionately to the overall catch rate. The estimated minimum number of total seabirds caught in New Zealand waters declined from 3,652 in 1988 to 360 in 1992, probably as a result of mitigation measures introduced progressively by the industry and by government regulation. Use of tori lines to prevent birds seizing baits had an effect, as did setting in total darkness in the south. Considerably more work needs to be done on the development of improved mitigation measures. Greater observer coverage is required to measure accurately the mortality of individual seabird species on tuna longlines throughout the Southern Ocean and to determine the effectiveness of mitigation measures.

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Nel, Deon C., Peter G. Ryan, and Barry P. Watkins. "Seabird mortality in the Patagonian toothfish longline fishery around the Prince Edward Islands, 1996–2000." Antarctic Science 14, no. 2 (June 2002): 151–61. http://dx.doi.org/10.1017/s0954102002000718.

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Sanctioned longline fishing for Patagonian toothfish around the Prince Edward Islands (a globally important seabird breeding site) commenced in 1996 following high levels of Illegal, Unregulated and Unreported (IUU) fishing. Independent fishery observers accompanied all but two sanctioned trips between 1996 and 2000, allowing a thorough understanding of the impact of this fishery on seabirds. Overall, white-chinned petrels Procellaria aequinoctialis were by far the most frequently killed species. However, during the first year, when lines were set during the day and night, a significant number of albatrosses (particularly grey-headed albatrosses Thalassarche chrysostoma) were also killed. Birds were caught almost exclusively during their breeding seasons and most birds killed were breeding adult males from the Prince Edward Islands. Albatrosses and giant petrels were caught almost exclusively during day sets, whereas catch rates of white-chinned petrels did not differ between day and night sets. Albatrosses were caught closer to the islands than white-chinned petrels. Most white-chinned petrel carcasses were hooked in their wings and bodies, whereas albatrosses were caught most frequently in their bills and contained large numbers of baits. Rates of seabird bycatch in the sanctioned fishery decreased from 0.19 birds per 1000 hooks to 0.034 birds per 1000 hooks during the time of this study. This was probably mainly due to stricter implementation of mitigation measures and a progressive movement farther away from the islands over the years. We estimate that the combined impact of legal and IUU longline fishing around the Prince Edward Islands over the past four years could have resulted in between 7000 and 17 000 seabird mortalities and could have had significant impacts on the breeding populations of several seabird species breeding on the Prince Edward Islands. This was mainly due to high levels of IUU fishing during 1996/97.

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Paz, Jesica Andrea, Juan Pablo Seco Pon, Marco Favero, Gabriel Blanco, and Sofía Copello. "Seabird interactions and by-catch in the anchovy pelagic trawl fishery operating in northern Argentina." Aquatic Conservation: Marine and Freshwater Ecosystems 28, no. 4 (May 14, 2018): 850–60. http://dx.doi.org/10.1002/aqc.2907.

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Green, David B., Norbert T. W. Klages, Robert J. M. Crawford, Janet C. Coetzee, Bruce M. Dyer, Gavin M. Rishworth, and Pierre A. Pistorius. "Dietary change in Cape gannets reflects distributional and demographic shifts in two South African commercial fish stocks." ICES Journal of Marine Science 72, no. 3 (November 23, 2014): 771–81. http://dx.doi.org/10.1093/icesjms/fsu203.

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Abstract Seabirds are upper trophic level predators, and are often highly sensitive to changes in the availability of their prey. Altered prey assemblages resulting from fluctuations in oceanographic conditions may be mirrored by shifts in seabird diet. Long-term studies of dietary change in seabirds therefore provide valuable insight into the nature of environmental shifts within the systems in which they forage. In recent decades, the Agulhas region in South Africa has undergone significant oceanographic change related to warming and intensification of the Agulhas current. Concurrent with this change, the population of Cape gannets Morus capensis at Bird Island, Algoa Bay, has grown rapidly, probably as a result of an increased availability of its dominant prey items, sardine Sardinops sagax and anchovy Engraulis encrasicolus. Using one of the longest and most complete time-series available on diet of a seabird (spanning 34 years), we tested for changes in composition and the abundance of dominant prey species of this population. These observed changes were also compared with acoustic survey estimates of their biomass, and annual catch data. Since 1979, the prey composition has remained similar, but the dietary contribution of sardine and anchovy, which fluctuated inversely to each other, increased over the study period. These shifts seem to be reflective of fluctuations in the stock size of sardine and anchovy. Conversely, a third species, saury Scomberesox saurus, dominant in the non-breeding diet of the 1980s, decreased significantly in dietary abundance over the following two decades. It is likely that dietary shifts of Cape gannets at Bird Island were related to climate-mediated oceanographic change. The implications of such changes are discussed.

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Clark, Bethany L., Freydís Vigfúsdóttir, Mark J. Jessopp, Julian M. Burgos, Thomas W. Bodey, and Stephen C. Votier. "Gannets are not attracted to fishing vessels in Iceland—potential influence of a discard ban and food availability." ICES Journal of Marine Science 77, no. 2 (December 4, 2019): 692–700. http://dx.doi.org/10.1093/icesjms/fsz233.

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Abstract Fisheries produce large amounts of waste, providing food subsidies for scavengers. Discards influence seabird movement, demography and community structure, but little is known about seabird–fishery interactions where discarding is banned. Here, we investigate how northern gannets Morus bassanus respond to fishing vessels in Iceland, where discarding commercial species is illegal, but birds may still access bait, offal, or catch. We GPS-tracked 82 foraging trips for 36 breeding gannets from two colonies (Skrúður and Hellisey) and obtained time-matched vessel locations. We classified bird behaviour using Hidden Markov Models and then tested the effect of vessel distance on behavioural state-switching using multi-state Markov models. Fishing vessels were present during 94% of foraging trips. However, the likelihood of gannets switching from travelling to foraging was unaffected by vessel proximity, regardless of gear type or activity. When encountering vessels, gannets rarely foraged but instead were more likely to continue travelling. When controlling for population size, gannet foraging trips at both colonies were shorter than expected, suggesting favourable conditions. The lack of behavioural responses to vessels among Icelandic gannets is likely driven by the discard ban and availability of pelagic fishes. Our findings have implications for understanding bycatch risk and the consequences of discard reforms.

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Goetz, Sabine, Martín Laporta, Julio Martínez Portela, M. Begoña Santos, and Graham J. Pierce. "Experimental fishing with an “umbrella-and-stones” system to reduce interactions of sperm whales (Physeter macrocephalus) and seabirds with bottom-set longlines for Patagonian toothfish (Dissostichus eleginoides) in the Southwest Atlantic." ICES Journal of Marine Science 68, no. 1 (November 11, 2010): 228–38. http://dx.doi.org/10.1093/icesjms/fsq161.

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Abstract Goetz, S., Laporta, M., Martínez Portela, J., Santos, M. B., and Pierce, G. J. 2011. Experimental fishing with an “umbrella-and-stones” system to reduce interactions of sperm whales (Physeter macrocephalus) and seabirds with bottom-set longlines for Patagonian toothfish (Dissostichus eleginoides) in the Southwest Atlantic. – ICES Journal of Marine Science, 68: 228–238. Depredation, i.e. the damage or removal, of Patagonian toothfish (Dissostichus eleginoides) from longlines by sperm whales (Physeter macrocephalus) can cause considerable economic loss for Spanish fishing vessels in the Southwest Atlantic. The fishery also suffers high bycatch rates of seabirds. The main goal of the study was to assess the extent of depredation and seabird bycatch and to test the potential of the so-called “umbrella” system, coupled with attached stones for faster sinking, for minimizing both. Moreover, we investigated the relationships between sightings of sperm whales, depredation, catches, and environmental variables using generalized additive modelling. Data were collected during 297 hauls on a longliner in 2007/2008 in international waters of the Southwest Atlantic. Sperm whales were sighted during 35% of the hauls, always during gear retrieval, and their presence was positively related to fish damage. The overall depredation rate (0.44% of the total catch) was low, but is assumed to be underestimated because sperm whales were suspected of also taking fish without leaving visual evidence. The “umbrella-and-stones” system was highly effective in preventing bycatch and appeared to restrict depredation, but significantly reduced the catches. The results demonstrate that there is still some way to go to solve the problem of depredation.

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Ian F., West, Janic Molloy, Michael F. Donoghue, and Chris Pugsley. "Seabird and Marine Mammal Bycatch Reduction Through Fishing Industry Funded Research: The New Zealand Conservation Services Levy Program." Marine Technology Society Journal 33, no. 2 (January 1, 1999): 13–18. http://dx.doi.org/10.4031/mtsj.33.2.3.

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Since 1995 the New Zealand government has implemented a scheme to recover from the domestic commercial fishing industry the funding required to investigate and mitigate the impacts of fishing on protected species of marine wildlife. Conservation Services Levies are approved by the Minister of Conservation, administered by the Department of Conservation (DOC), and are collected by the Ministry of Fisheries. The levies are set annually following extensive consultation between the relevant government agencies and stakeholder groups. Levies are primarily used to boost observer coverage in selected fisheries, to monitor the status of protected species known to be incidentally taken in fishing operations, and to develop ways of mitigating the by-catch of species protected under the New Zealand Marine Mammals Protection Act 1978 and the Wildlife Act 1953. Conservation Services Levies provide a rare example in the global fishing industry of a transparent and accountable process, requiring the industry to pay at least part of the true environmental costs of its operation. It would be premature to suggest that the introduction of these levies has achieved a resolution of the various interactions between commercial fisheries and protected species of marine wildlife.

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Miller, Timothy J., John R. Skalski, and James N. Ianelli. "Optimizing a stratified sampling design when faced with multiple objectives." ICES Journal of Marine Science 64, no. 1 (November 13, 2006): 97–109. http://dx.doi.org/10.1093/icesjms/fsl013.

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Abstract Miller, T. J., Skalski, J. R., and Ianelli, J. N. 2007. Optimizing a stratifield sampling design when faced with multiple objectives – ICES Journal of Marine Science, 64, 97–109. For many stratified sampling designs, the data collected are used by multiple parties with different estimation objectives. Quantitative methods to determine allocation of sampling effort to different strata to satisfy the often disparate estimation objectives are lacking. Analytical results for the sampling fractions and sample sizes for primary units within each stratum of a stratified (multi-stage) sampling design that are optimal with respect to a weighted sum of relative variances for the estimation objectives are presented. Further, an approach for assessing gains or losses for each estimation objective by changing allocation of sample sizes to each stratum is provided. As an illustration, the analytical results are applied to determine optimal observer sampling fractions (coverage rates) for the North Pacific Groundfish Observer Programme (NPGOP), for which the multiple objectives are assumed to be bycatch (seabird, marine mammal, and non-targeted fish species) and total catch, and catch-at-length and -age of targeted fish species. Simultaneously optimizing a criterion that defines the strata of the NPGOP sampling design is also considered. When observer coverage rates are allowed to be gear-specific for the NPGOP design, the optimized objective function is between 10% and 28% less than the value corresponding to current sampling for annual data (2000–2003) and 12% less when optimized over all years combined.

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Ryan, Peter G. "The taxonomic and conservation status of the Spectacled Petrel Procellaria conspicillata." Bird Conservation International 8, no. 3 (September 1998): 223–35. http://dx.doi.org/10.1017/s0959270900001891.

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SummaryThe Spectacled Petrel Procellaria [aequinoctialis] conspicillata only breeds at Inaccessible Island, central South Atlantic Ocean. During the early 1980s the population was estimated to be at most 1,000 pairs, but hundreds of Spectacled Petrels have been killed annually in longline fisheries off the east coast of South America since at least 1987. Although the population is characterized by a unique plumage trait, it is still regarded as a subspecies of the White-chinned Petrel P. aequinoctialis. Analysis of calls and playback experiments show that the Spectacled Petrel is vocally distinct from White-chinned Petrels and should be regarded as a valid biological species. It is also slightly smaller and breeds earlier than the White-chinned Petrel. Given its small population size and known mortality on longlines, the Spectacled Petrel is Endangered in terms of IUCN criteria C1 and C2b. Longline fisheries operating off South America should institute measures to reduce seabird by-catch. A survey of the breeding population at Inaccessible Island is required to assess the rate at which the population is decreasing.

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Gallo-Cajiao, Eduardo. "Evidence is required to address potential albatross mortality in the New South Wales Ocean Trawl fishery." Pacific Conservation Biology 20, no. 3 (2014): 328. http://dx.doi.org/10.1071/pc140328.

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To examine the current management of trawl fisheries is important to ensure albatross mortality is not being overlooked. By-catch of albatrosses in trawl fisheries occurs cryptically, which has hindered the development of conservation policy. The implementation of tasked seabird observer programmes in trawl fisheries, nevertheless, has shown that albatross mortality can happen at threatening levels. Consequently, mitigation measures have been developed and adopted in some trawl fisheries. Despite this, some trawl fisheries lack clear policy in relation to albatross mortality. In this context, I investigated the management of potential albatross mortality in a state trawl fishery, the New South Wales Ocean Trawl, in Australia. I conducted a literature search and addressed a set of questions to the responsible management agency through questions on notice at the State Parliament of New South Wales to understand albatross interactions from a policy standpoint. My results indicate that current policy neither encompasses albatross mortality nor is evidence-based. However, the combination of characteristics of this fishery and its overlap with albatross occurrence, along with the reported albatross mortality from other trawl fisheries, may warrant the need to collect empirical evidence on potential albatross interactions. Hence, the responsible management agency should take action according to legal obligations. In this scenario, I recommend the implementation of a tasked seabird observer programme, collection of baseline data, and adoption of adaptive management by the examined fishery. As uncertainty can hamper conservation efforts because management actions require evidence, it is imperative to fill current information gaps in this fishery. Additionally, an improved understanding of albatross mortality from individual trawl fisheries across different fisheries management jurisdictions will enable the prioritization of conservation efforts of this avian taxon in an international and multi-gear fishing context.

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Brown, Judith, Paul Brickle, Sarah Hearne, and Gemma French. "An experimental investigation of the ‘umbrella’ and ‘Spanish’ system of longline fishing for the Patagonian toothfish (Dissostichus eleginoides) in the Falkland Islands: Implications for stock assessment and seabird by-catch." Fisheries Research 106, no. 3 (December 2010): 404–12. http://dx.doi.org/10.1016/j.fishres.2010.09.013.

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Hamer, Derek J., Simon J. Childerhouse, John P. McKinlay, Mike C. Double, and Nick J. Gales. "Two devices for mitigating odontocete bycatch and depredation at the hook in tropical pelagic longline fisheries." ICES Journal of Marine Science 72, no. 5 (March 24, 2015): 1691–705. http://dx.doi.org/10.1093/icesjms/fsv013.

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Abstract Odontocete bycatch on and depredation from tropical pelagic longlines is globally widespread, having negative impacts on the economic viability of affected fisheries and on the conservation of affected odontocete populations. Reports by fishers that depredating odontocetes avoid gear tangles has underpinned the development of simulated structures to physically deter depredating odontocetes. This study assessed the efficacy of two such devices developed to mitigate odontocete depredation and associated bycatch. Of particular interest was their impact on (i) soak depth and (ii) sink rate using truncated trials, before determining their impact under full operational conditions on rates of (iii) catch of the five most economically important fish, and (iv) odontocete depredation and bycatch, on changes in (v) fish survival and size, and (vi) setting and hauling speed. The results indicated that the inclusion of devices on longlines had negligible impact on soak depth, thus were unlikely to impact on the suite of fish specifically targeted and caught. The sink rate was slowed, perhaps by drag, trapped air, or propeller wash, although the addition of weight might remedy this if the devices were to be used in areas where seabird bycatch could occur. Most importantly, trials conducted in Australian and in Fijian waters indicated that pooled fish catch rates (i.e. albacore, yellowfin, bigeye, mahi mahi, and wahoo) increased in the presence of the devices, possibly because more fish were attracted by them or because more depredators were deterred. Catch rates on control gear next to gear with devices attached were higher than more distant control gear, suggesting the influences of the devices may have extended to adjacent branchlines. The size of caught fish was mostly unaffected, although the survival of yellowfin and bigeye increased significantly in the presence of the devices. Hauling was slowed by the use of the devices and the need for an extra crewmember during setting and hauling, which could be cost prohibitive in some fisheries, especially if economic benefits from their use are not obvious. Despite the small sample size, odontocete bycatch only occurred on unprotected fishing gear and all individuals were released alive, although their fate was uncertain; there was evidence of injuries sustained from the event. The outcomes are positive and should motivate stakeholders to view such devices as a potentially effective tool for mitigating odontocete bycatch and depredation in this and similar longline fisheries. Future efforts should focus on improving operational integration and reducing implementation costs to encourage voluntary uptake and thus avoid non-compliance and the need for costly monitoring. The use of this technology could bring about marked improvements to the conservation situation for affected odontocete populations and to the economic situation for affected longline fisheries.

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Lynam, Christopher P., Nicholas C. Halliday, Hannes Höffle, Peter J. Wright, Cindy J. G. van Damme, Martin Edwards, and Sophie G. Pitois. "Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950–2005." ICES Journal of Marine Science 70, no. 3 (February 18, 2013): 540–53. http://dx.doi.org/10.1093/icesjms/fst006.

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Abstract Lynam, C. P., Halliday, N. C., Höffle, H., Wright, P. J., van Damme, C. J. G., Edwards, M., and Pitois, S. 2013. Spatial patterns and trends in abundance of larval sandeels in the North Sea: 1950–2005 – ICES Journal of Marine Science, 70: 540–553. Early recruitment indices based on larval fish data from the Continuous Plankton Recorder (CPR) have the potential to inform stock assessments of Ammodytes marinus in the North Sea. We evaluate whether the CPR data are reliable for sandeel larvae. Spatially, CPR larval data were comparable with catches by dedicated larval samplers (Gulf and bongo nets) during ICES coordinated surveys in 2004 and 2009. ICES data are also used to explore environmental influences on sandeel distributions. Temporally, CPR data correlate with larval data from plankton surveys off Stonehaven (1999–2005), with sandeel 0-group trawl data at the east Fair Isle ground (since 1984), and with recruitment data (since 1983) for the Dogger Banks stock assessment area. Therefore, CPR data may provide an early recruit index of relative abundance for the Dogger Banks assessment area, where the majority of the commercial catch of A. marinus is taken, and the Wee Bankie area that is particularly important for seabird foraging. While warm conditions may stimulate the production of sandeel larvae, their natural mortality is typically greater, in the Dogger Banks and Wadden Sea areas, when the larvae are hatched in warm years and/or with abundant 1-year-old sandeel that are likely to be cannibalistic.

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31

Greenstreet, Simon P. R., Eric Armstrong, Henrik Mosegaard, Henrik Jensen, Iain M. Gibb, Helen M. Fraser, Beth E. Scott, Gayle J. Holland, and Jonathan Sharples. "Variation in the abundance of sandeels Ammodytes marinus off southeast Scotland: an evaluation of area-closure fisheries management and stock abundance assessment methods." ICES Journal of Marine Science 63, no. 8 (January 1, 2006): 1530–50. http://dx.doi.org/10.1016/j.icesjms.2006.05.009.

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Abstract In 2000, a sandeel fishery off SE Scotland, which commenced in the early 1990s, was closed in response to concerns that the fishery was having a deleterious effect on seabird breeding performance at colonies in the vicinity of the fishing grounds. Fishery-derived catch per unit effort (cpue) data are used together with three different fishery-independent survey techniques (acoustic, demersal trawl, and nocturnal grab survey) to assess variation in sandeel Ammodytes marinus population biomass in the area over the period 1997–2003, a period that included the last three years that the fishery was operating and the first four years of the sandeel fishing moratorium. Temporal trends in estimates of sandeel biomass derived from these different assessment methods were inconsistent and, on the basis of these alone, it was not possible to determine whether sandeel population biomass in the area had increased following the closure of the fishery. The different survey methods assess different components of the sandeel population; acoustic survey and fishery cpue quantified sandeels active in the water column, whilst demersal trawl survey quantified sandeels buried in the sediments. These data were collected at a time of year when sandeels were moving between the seabed sediments and the overlying water column. A grab survey also quantified sandeels buried in the sediment, but these data were collected at a time of year when the entire population should have been buried in the sediment. Differences between the different time-series were reconciled by taking account of the cumulative total primary production in each year prior to the surveys. On the basis of this, a model was developed that utilized acoustic and demersal trawl survey data to estimate the total sandeel population biomass. This model was validated using the nocturnal grab-survey data. The modelled data indicated that the biomass of sandeels 1+ years old increased sharply in the first year of the closure and remained higher in all four of the closure years than in any of the preceding three years, when the fishery was operating. The biomass of 0-group sandeels in three of the four closure years exceeded the biomass present in the three years of commercial fishing. Whereas the response of 1+ sandeels may have been a direct consequence of the closure, this is not likely to have been the case in respect of 0-group sandeels. The closure appears to have coincided with a period of enhanced recruit production.

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Arana, Patricio M., and Renzo Rolleri. "Incidental catch of marine organisms registered in the Chilean Antarctic krill fishery, years 2012-2016." Latin American Journal of Aquatic Research 48, no. 3 (July 6, 2020): 429–39. http://dx.doi.org/10.3856/vol48-issue3-fulltext-2434.

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Krill (Euphausia superba) catch is currently the most relevant fishery industry in Antarctic waters. This resource is a keystone species in the Antarctic food web, sustaining the contribution to the trophic ecology of many invertebrate and vertebrate species. To catch krill, part of the fleet in this fishery uses large mid-water nets that also retain a diversity of other organisms like plankton, meroplankton, and fish species as bycatch. Therefore, it is necessary to understand and evaluate the magnitude of this incidental catch, as well as the potential interactions between krill fishing gear with seabirds and mammals. To estimate the composition and extent of bycatch for this fishery included 784 samples of 25 kg and an equal number of 1 kg sub-samples obtained from Antarctic krill catches in Subarea 48, between years 2012 and 2016. A total of 15 fish species were identified along with the record of five other taxa and other unidentified specimens. The most relevant fish species bycaught by weight were mackerel icefish Champsocephalus gunnari, South Georgia icefish Pseudochaenichthys georgianus, and painted notie Lepidonotothen larseni. Additionally, 20 interactions with seabirds and nine interactions with Antarctic fur seals (Arctocephalus gazella) were registered. In the five years of operations, only three seabirds died, and only two individuals of A. gazelle caught by the net were killed.

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Huang, Hsiang-Wen. "Incidental catch of seabirds and sea turtles by Taiwanese longline fleets in the Pacific Ocean." Fisheries Research 170 (October 2015): 179–89. http://dx.doi.org/10.1016/j.fishres.2015.06.004.

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34

Buttemer, William A., Harry Battam, and A. J. Hulbert. "Fowl play and the price of petrel: long-living Procellariiformes have peroxidation-resistant membrane composition compared with short-living Galliformes." Biology Letters 4, no. 4 (May 20, 2008): 351–54. http://dx.doi.org/10.1098/rsbl.2008.0145.

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The membrane pacemaker hypothesis predicts that long-living species will have more peroxidation-resistant membrane lipids than shorter living species. We tested this hypothesis by comparing the fatty acid composition of heart phospholipids from long-living Procellariiformes (petrels and albatrosses) to those of shorter living Galliformes (fowl). The seabirds were obtained from by-catch of commercial fishing operations and the fowl values from published data. The 3.8-fold greater predicted longevity of the seabirds was associated with elevated content of peroxidation-resistant monounsaturates and reduced content of peroxidation-prone polyunsaturates and, consequently, a significantly reduced peroxidation index in heart membrane lipids, compared with fowl. Peroxidation-resistant membrane composition may be an important physiological trait for longevous species.

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35

Lowry, Michael, and Jeff Murphy. "Monitoring the recreational gamefish fishery off south-eastern Australia." Marine and Freshwater Research 54, no. 4 (2003): 425. http://dx.doi.org/10.1071/mf01269.

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The east coast Australian gamefish fishery is a diverse, multi-species fishery that targets billfish, sharks, tuna and other pelagic fish along the east Australian seaboard. A Gamefish Tournament Monitoring Program (GTMP) was undertaken, and 39021 angler trips from 1996 to 2000 were analysed. The program reports on trends in fishing effort, catch rates, catch composition, proportions of captures tagged and released and spatial distribution of catches for the principal recreational billfish species: black marlin (Makaira indica), striped marlin (Tetrapterus audax) and blue marlin (Makiara nigricans).The GTMP was principally designed as part of an integrated program to monitor the recreational gamefish fishery. The spatial and temporal design of the program restricted statistical analyses however, there were trends in fishing effort, directed effort, catch rates, catch composition, proportions of fish tagged and spatial distribution of catches for the principal recreational billfish species over seven successive years (1994–2000). Analysis of catch data, stratified by directed effort, indicated significant differences in catches of target species, demonstrating the importance of calculating catch rate estimates according to the main target preference. Analysis of tournament based tagging information indicated that while overall tournament tagging rates remained high (88%) there were significant differences in the number of fish tagged between species groups highlighting the impact that angler attitude and the competition point score structure has on the harvest of gamefish target species.

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Svane, Ib. "Occurrence of dolphins and seabirds and their consumption of by-catch during prawn trawling in Spencer Gulf, South Australia." Fisheries Research 76, no. 3 (December 2005): 317–27. http://dx.doi.org/10.1016/j.fishres.2005.07.012.

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Klaer, Neil, and Tom Polacheck. "By-catch of Albatrosses and other Seabirds by Japanese Longline Fishing Vessels in the Australian Fishing Zone from April 1992 to March 1995." Emu - Austral Ornithology 97, no. 2 (June 1997): 150–67. http://dx.doi.org/10.1071/mu97019.

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Klaer, Neil, and Tom Polacheck. "The Influence of Environmental Factors and Mitigation Measures on By-Catch Rates of Seabirds by Japanese Longline Fishing Vessels in the Australian Region." Emu - Austral Ornithology 98, no. 4 (December 1998): 305–16. http://dx.doi.org/10.1071/mu98042.

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39

He, Pingguo, Christopher Rillahan, and Vincent Balzano. "Reduced herding of flounders by floating bridles: application in Gulf of Maine Northern shrimp trawls to reduce bycatch." ICES Journal of Marine Science 72, no. 5 (December 23, 2014): 1514–24. http://dx.doi.org/10.1093/icesjms/fsu235.

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Abstract We hypothesized that a floating trawl bridle that does not contact the seabed would reduce the herding of fish, especially bottom dwelling flounders, and thus reduce bycatch of these fish in shrimp trawls. We further hypothesized that, due to the non-herding nature of northern shrimp (Pandalus borealis), the use of an off-bottom floating bridle would not reduce shrimp catch. These hypotheses were tested in the field by comparing a trawl with regular bottom-tendering wire bridles and the same trawl with floating synthetic bridles in the Gulf of Maine northern shrimp fishery. As expected, no statistically significant differences in catch rates and size were found for the targeted northern shrimp (146.3 ± 10.58 kg h−1 control vs. 140.8 ± 9.35 kg h−1, p = 0.13). Total finfish bycatch was reduced by 14.9%, and the difference was statistically different (p = 0.01). The most important reduction was the catch of juvenile American plaice (Hippoglossoides platessoides) with a significant reduction of 20.0% (p = 0.01). For witch flounder (Glyptocephalus cynoglossus), a reduction of 19.3% was found, but it was not statistically significant (p = 0.14). The reduction of Acadian redfish (Sebastes fasciatus) (by 28.0%, p = 0.02) was also statistically different. Catch of targeted silver hake (Merluccius bilinearis) was reduced by 10.8%, but the difference was only marginally significant (p = 0.07). An analysis of length frequencies for the targeted shrimp and major bycatch species revealed no size-related selection between the gears with regular bridles and floating bridles. The reductions in flounder bycatch indicate reduced herding of benthic species when the bridles are kept off bottom. This easy modification may be readily adopted in the northern shrimp fisheries in the North Atlantic, and can also possibly be applied in other shrimp and prawn fisheries with further experimentation.

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40

Jarocki, Walenty. "WAVE EFFECT ON THE COAST FORMATION AND EROSION." Coastal Engineering Proceedings 1, no. 7 (January 29, 2011): 12. http://dx.doi.org/10.9753/icce.v7.12.

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Various authors explain differently the mechanism of action of waves on the_ sediment movement. Some authors consider that the waves are raising the soil fractions from the bottom and water currents transfer them along the seaboard. The other authors suppose that each wave shears some soil in the bottom in littoral zone of the waves and wind is oblique to the shoreline. Beach currents catch and transport the sediment particles along the seaboard. These authors suppose when the wind is in the direction of seaboard /from sea/ then the bottom currents move in the opposite direction. These currents transport the ground particles in the direction of sea and thus the seaboard erosion arises. When the wind direction is opposite, the botto currents arise in the direction of seaboard and they cause the transportation of ground and the accumulation of seaboards. These reasons show that the action of waves would cause only the separation of ground particles and their asoeading. Our last investigations and observations of the sediment movement have led the conclusion that the waves may cause the raise of the sediment partciles and also their transport. The character of this transport depends on the wave kind and on the height and length of waves. General quantity of the lifted particles by means of waves increases as the power of waves or height and length of waves increases. If the power of waves decreases these particles fall. The waves are able to transport the bed load and detritus load without cooperation of the water current in spite of horizontal or inclined bottom. Under the action of waves the sediment moves the oscillatory movement. The waves move the bed load in the shallow exterior zones with the horizontal bottom only, towards the wave propagation. This material may be moved perpendicular the slope, according to the wave direction or in the opposite on< If the approaching wave creates the acute angle to the shoreline then the bed load moves near the seaboard. The transport of the bed load and of detritus loai change if the water current and waves appear simultaneously. The water current acts generally on the detritus load because the water moves this material easier than the bed load which rolls on the bottom.

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Geraldi, Nathan R., Richard A. Wahle, and Michael Dunnington. "Habitat effects on American lobster (Homarus americanus) movement and density: insights from georeferenced trap arrays, seabed mapping, and tagging." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 3 (March 2009): 460–70. http://dx.doi.org/10.1139/f09-011.

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Understanding the influence of heterogeneous marine landscapes on the movements of benthic megafauna is often hampered by limited spatial resolution and insufficient sample size. Here, we combined the benefits of seabed mapping, georeferenced trap arrays, and conventional tagging methods to quantify the effect of substrate on movements of the American lobster ( Homarus americanus ). In total, 21 848 lobsters were tagged, and movements were tracked among spatially referenced research and commercial traps. We found that lobster densities from diver surveys were highest on rocky habitat, but catch rates in traps were highest on unstructured sediment, resulting in traps on level bottom having a larger effective fishing area than traps on structurally complex habitat. Moreover, tag returns indicated that lobsters initially caught and released on sediment moved farther and faster than those initially caught in traps on rocky substrate. These observations are consistent with previous reports of the existence of a dichotomy of transient and resident lobsters in coastal populations, but the association of movement with habitat type was unknown. Our results indicate that field studies integrating conventional trapping, visual census, and tagging with seabed mapping can efficiently generate high-resolution information on habitat-related behavior of large samples of benthic organisms.

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Eigaard, Ole R., Francois Bastardie, Mike Breen, Grete E. Dinesen, Niels T. Hintzen, Pascal Laffargue, Lars O. Mortensen, et al. "Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions." ICES Journal of Marine Science 73, suppl_1 (June 9, 2015): i27—i43. http://dx.doi.org/10.1093/icesjms/fsv099.

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Abstract This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam trawl groups, two demersal seine groups, and one dredge group), for which we established gear “footprints”. The footprint of a gear is defined as the relative contribution from individual larger gear components, such as trawl doors, sweeps, and groundgear, to the total area and severity of the gear's impact. An industry-based survey covering 13 countries provided the basis for estimating the relative impact-area contributions from individual gear components, whereas sediment penetration was estimated based on a literature review. For each gear group, a vessel size–gear size relationship was estimated to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km 2 h −1 of which 0.08 km 2 has an impact at the subsurface level (sediment penetration ≥ 2 cm). Beam trawling for flatfish ranks low when comparing overall footprint size/hour but ranks substantially higher when comparing only impact at the subsurface level (0.19 km 2 h −1 ). These results have substantial implications for the definition, estimation, and monitoring of fishing pressure indicators, which are discussed in the context of an ecosystem approach to fisheries management.

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Durán Muñoz, P., M. Sayago-Gil, T. Patrocinio, M. González-Porto, F. J. Murillo, M. Sacau, E. González, G. Fernández, and A. Gago. "Distribution patterns of deep-sea fish and benthic invertebrates from trawlable grounds of the Hatton Bank, north-east Atlantic: effects of deep-sea bottom trawling." Journal of the Marine Biological Association of the United Kingdom 92, no. 7 (April 3, 2012): 1509–24. http://dx.doi.org/10.1017/s002531541200015x.

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Distributions of deep-sea fish, benthic invertebrates and the effects of deep-sea bottom trawling were studied based on data collected in 2005 from a joint collaboration survey undertaken between the Spanish Institute of Oceanography and a deep-sea trawler on the Hatton Bank (north-east Atlantic). A total of 163 valid bottom trawl hauls (600–1600 m) were analysed. The main trawlable grounds were located on the sedimentary seabed of the western flank of the bank (Hatton Drift). Grenadiers and smoothheads were predominant in the trawl catches (67% and 11.8% by weight respectively). Both species were abundant along the western flank. Deep-water sharks accounted for 7.4% of weight, and were abundant along the south-eastern slopes. Chimerids, lotids, morids and other deep-sea species were also taken as by-catch. Grenadiers and deep-water sharks dominated the discards. By-catches of cold-water corals were generally associated with the rocky outcrop and were more abundant at the top of the bank. Abundant by-catches of large sponges, characteristic of sponge-dominated biotopes, were taken from the eastern flank.

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Devney, Carol A., Michael Short, and Bradley C. Congdon. "Cyclonic and anthropogenic influences on tern populations." Wildlife Research 36, no. 5 (2009): 368. http://dx.doi.org/10.1071/wr08142.

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Organisms can be strongly affected by a range of natural and anthropogenic stressors in conjunction, making comprehensive assessments of multiple potential drivers of population dynamics essential. An 18-year dataset obtained for Michaelmas Cay in the northern Great Barrier Reef, Australia, was used to assess population trends for three tern species relative to two potential threatening processes, namely human impacts (as either commercial fishing or tourism) and cyclone activity. We found a positive, 2-year lagged relationship between long-line catch per unit effort in the Eastern Tuna and Billfish Fishery in the vicinity of Michaelmas Cay and breeding participation in the two pelagic foraging terns, but not in the inshore foraging tern. The abundance of large pelagic fish may influence recruitment into the breeding populations of the two pelagic terns in the following years through impacts on prey availability. Long-term population trends for all seabirds were not related to localised direct disturbance from cyclones or associated changes in cay size and/or nesting habitat. Current management protocols in place for the tourism industry at the cay appear to be minimising direct human impacts. Other evidence from this breeding location suggesting that climate variation may be driving foraging success and breeding-population dynamics in the two pelagic terns implies that a precautionary approach is warranted to the management of any potential stressors to birds in this system.

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Celli, Daniele, Yuzhu Li, Muk Chen Ong, and Marcello Di Risio. "Random Wave-Induced Momentary Liquefaction around Rubble Mound Breakwaters with Submerged Berms." Journal of Marine Science and Engineering 8, no. 5 (May 9, 2020): 338. http://dx.doi.org/10.3390/jmse8050338.

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The effects of submerged berms in attenuating the momentary liquefaction beneath rubble mound breakwaters under regular waves were investigated in a recent study. The present work aims to investigate the momentary liquefaction probabilities around and beneath breakwaters with submerged berms under random waves. The interaction between waves and breakwaters with submerged berms has been simulated through a phase-resolving numerical model. The soil response to the seabed pressure induced by random waves has been investigated using a poro-elastic soil solver. For three different breakwater configurations, the liquefaction depths under random wave conditions have been compared with those cases under representative regular waves. In the present study, the offshore spectral wave height ( H m 0 ) and the peak period ( T p ) of irregular waves are used as representative regular wave parameters. Results reveal the importance of considering random waves for a safe estimation of the momentary liquefaction probability. Indication about the minimum number of random waves, which is required to properly catch the liquefaction occurrences, has been also addressed.

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Pennino, Maria Grazia, Elena Guijarro-García, Raul Vilela, José Luis del Río, and Jose Maria Bellido. "Modeling the distribution of thorny skate (Amblyraja radiata) in the southern Grand Banks (Newfoundland, Canada)." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 11 (November 2019): 2121–30. http://dx.doi.org/10.1139/cjfas-2018-0302.

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Globally, commercial fisheries have had a strong impact on elasmobranch populations directly through high catch rates and indirectly through bycatch. Consequently, the abundance of many species is declining to the extent that some are considered under threat of extinction. Regionally, this negative trend is also evident in the international waters of the southern Grand Banks (off the coast of Newfoundland, Canada), where the occurrence of the thorny skate (Amblyraja radiata) has declined by nearly 70% in recent decades. This study used Bayesian species distribution models to investigate the habitat preference and biomass trends of the thorny skate during a 14-year period (2003–2017), linking five environmental predictors (i.e., bathymetry, sea bottom temperature, seabed aspect, slope, and rugosity) and prey distribution with fishery-independent data. Our findings identify some of the sensitive habitats for this species and the ecological factors that may be driving its population dynamics in the area. We argue that knowledge about the factors influencing the distribution of this species and spatiotemporal effects could be exploited as potential mitigation measures for future fishery management strategies.

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Mutmainnah, Nafsul, Iis Nur Asyiah, and Ika Lia Novenda. "PEMANFAATAN ALAT TANGKAP IKAN TRADISIONAL OLEH NELAYAN PULAU BAWEAN KABUPATEN GRESIK." JURNAL PERIKANAN TROPIS 8, no. 1 (June 3, 2021): 23. http://dx.doi.org/10.35308/jpt.v8i1.1923.

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Bawean Island is located in the middle of the Java Sea, about 150 km north of Gresik. The name Bawean was taken from the Sanskrit which means there is sunlight. The Bawean people are acculturation from several ethnic groups of Java, Madura, Kalimantan, Sulawesi and Sumatera including their culture and language. The majority of Bawean residents work as fishermen. Bawean Island fishermen utilize marine resources to meet the needs of their family by using knowledge that has been obtained from previous generations. The purpose of this study was to determine the use of traditional fishing gear and fishing strategies used by fishing communities in Bawean Island. The research method used was direct observation, and sampling using Purposive Sampling and Snowball Sampling. The results showed that the fishing gears used by Bawean Island fishermen were kareket (waring), pajeng (payang), jhering cursor (ring net), rompon (bubu), jhering pemhir (drift gill net), payimbek rentengan (drag fishing), gerany Panyimbek (drag fishing line), panceng (fishing line). These fishing gears are very environmentally friendly because the usage does not damage the seabed ecosystem. Each fishing gear has its own characteristics, so that different fishing gear will result in different fishing catch

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Essington, Timothy E., Pamela E. Moriarty, Halley E. Froehlich, Emma E. Hodgson, Laura E. Koehn, Kiva L. Oken, Margaret C. Siple, and Christine C. Stawitz. "Fishing amplifies forage fish population collapses." Proceedings of the National Academy of Sciences 112, no. 21 (April 6, 2015): 6648–52. http://dx.doi.org/10.1073/pnas.1422020112.

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Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

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Zimmermann, Mark, Mark E. Wilkins, Kenneth L. Weinberg, Robert R. Lauth, and Franklin R. Shaw. "Influence of improved performance monitoring on the consistency of a bottom trawl survey." ICES Journal of Marine Science 60, no. 4 (January 1, 2003): 818–26. http://dx.doi.org/10.1016/s1054-3139(03)00043-2.

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Abstract Numerous trawl hauls, made during the triennial bottom trawl surveys (1977–1998) conducted by the National Marine Fisheries Service off the U.S. West Coast, had unusually small catch rates of benthic fish and invertebrates (cpueB), probably because the trawl failed to contact the seabed (off-bottom). Technological advances in the equipment used to monitor trawl performance since 1986 have increased our ability to recognize off-bottom tows, and cpueB has risen. As direct trawl performance measurements were not available in earlier surveys, a minimum cpueB derived from the survey with the best monitoring of bottom contact of the time-series (1998) was used as a criterion to eliminate trawls with poor bottom contact from earlier surveys. The truncated data sets produce significantly larger biomass indices, especially in 1980, with increases of 43, 45, and 56% for Dover sole, petrale sole, and Pacific sanddab, respectively. The analysis suggests that changes in cpueB over the time-series may be related more to changing survey fishing methods than to changes in abundance. Other bottom trawl surveys, which have also added trawl monitoring equipment during their time-series, may have experienced similar changes in trawl performance.

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Anders, Neil, Anders Fernö, Odd-Børre Humborstad, Svein Løkkeborg, and Anne Christine Utne-Palm. "Species specific behaviour and catchability of gadoid fish to floated and bottom set pots." ICES Journal of Marine Science 74, no. 3 (December 8, 2016): 769–79. http://dx.doi.org/10.1093/icesjms/fsw200.

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To increase our understanding of the interaction between fish and baited fishing gear we quantitatively described the behaviour of cod (Gadus morhua), saithe (Pollachius virens), and haddock (Melanogrammus aeglefinus) to baited pots in a fjord in northern Norway. Detailed video analyses were made to describe species specific responses and examine the effect of lifting the pot off the bottom. The majority of both cod and saithe approached the pots in an upstream direction, and fish approached floated pots higher in the water column than bottom set pots. Cod tended to approach a pot along the seabed and were more likely to encounter the bottom set pot than the floated pot, whereas saithe more often approached in the water column. The capture efficiency was low for all species, but cod were more likely to be caught than saithe and haddock. Cod showed a high encounter rate, low entrance rate and high escape rate. For saithe, a low encounter rate was the chief factor limiting capture efficiency. The observed differences between cod and saithe were explained by species-specific food-search strategies. No difference in entrance rate, escape rate or catch efficiency between the two pot types were found.

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Journal articles on the topic 'Seabird by-catch'

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