Estimating the odds of survival and identifying mitigation opportunities for common bycatch in pelagic longline fisheries

To evaluate how fishing practices affect bycatch survival and to identify opportunities to reduce bycatch mortality, we estimated the odds of hooking survival for common bycatch species in the Canadian longline fishery for swordfish (Xiphias gladius) and tunas (Thunnus spp.) fishing in the North Atlantic. Generalized linear models, with binomial response, were based on 859 sets observed between 2001 and 2004 and were tested using data from 2005 and 2006. Bycatch included targeted species in poor condition or below regulatory size limits. Odds of survival were two to five times higher for swordfish, yellowfin tuna (Thunnus albacares), pelagic stingray (Pteroplatytrygon violacea), porbeagle (Lamna nasus) and blue shark (Prionace glauca) caught on circle hooks compared to J-hooks during the 2001–2004 period. Further, odds of severe hooking injuries decreased for three shark species caught on circle hooks. We found no conservation benefit for loggerhead turtles (Caretta caretta) from circle hook use. Increased circle hook use coincided with increased targeting and higher landings of tunas. Hooking survival rates and, therefore opportunities to reduce bycatch mortalities differed among the 10 species commonly discarded or released. Where the odds of survival to the time of release are high (e.g., loggerhead turtles, pelagic stingray, blue shark), methods to reduce post-release mortality can be considered. Where the odds of hooking survival are low (e.g., swordfish and longnose lancetfish, Alepisaurus ferox), methods to reduce encounter rates would have greater conservation impact.     

Sea turtle by-catch in pelagic longline sets off southern Brazil

Results are presented on sea turtle by-catch observed in pelagic longline sets during research cruises in the south Atlantic in the vicinity of the shelf edge break in southern Brazil. The longline gear was set in a similar manner to that employed by the commercial longline fleet operating out of Santos, Brazil that targets swordfish, Xiphias gladius. Nineteen sea turtles were caught on 14 of 41 sets, which constituted a catch rate of 1.5 turtles per 1000 hooks. Thirty four percentage of all sets captured at least one turtle. The catch included loggerhead, Caretta caretta, leatherback, Dermochelys coriacea, and most likely olive ridley, Lepidochelys olivacea. All turtles, except one loggerhead, were captured live and released. Captures occurred during spring, summer and winter suggesting a year around presence and vulnerability. Given increased levels of longline effort directed at swordfish in the southeast Atlantic, substantial turtle by-catch can be expected. There is a critical need for additional information to be able to assess the potential impact on swordfish longline fisheries on sea turtle populations.     

Reducing incidental mortality of seabirds with an underwater longline setting funnel

A demersal longline fishery for Patagonian toothfish (Dissostichus eleginoides) that commenced off the Prince Edward Islands during 1996 has killed significant proportions of locally breeding albatrosses and petrels. As one of a suite of mitigation measures, we tested the efficacy of a Mustad underwater setting funnel to reduce incidental mortality of seabirds. The funnel, which deploys the longline 1-2 m beneath the sea surface, was used on 52% of 1714 sets (total effort 5.12 million hooks) over a 2-year period. Used in conjunction with a bird-scaring line, overall seabird bycatch rate was low (0.022 birds per 1000 hooks), and was dominated by white-chinned petrels (Procellaria aequinoctialis) (88% of the 114 birds killed). Bycatch rate was three times lower when the funnel was used both by day and at night. Daytime catch rates with the funnel were less than those attained during night sets without the funnel. In conjunction with other mitigation measures, underwater setting offers a significant reduction in seabird mortality in this fishery and could increase fishing efficiency by allowing daytime setting. However, small numbers of albatrosses were caught during daytime sets with the funnel, and its use for daytime sets should be closely monitored.     

At-sea distribution of breeding Tristan albatrosses Diomedea dabbenena and potential interactions with pelagic longline fishing in the South Atlantic Ocean

The endangered Tristan albatross Diomedea dabbenena is restricted to Gough and Inaccessible Islands. The species is killed as bycatch by longline fisheries in the South Atlantic, but the impact of this mortality is unknown. We satellite tracked 38 breeding Tristan albatrosses and assessed the seasonal and annual at-sea distribution of these birds in relation to reported pelagic longline fishing effort. These birds ranged across the South Atlantic from 50°W to 15°E with most (97%) daytime satellite fixes between latitudes 30°S and 45°S. Considerable fishing effort occurred within the same latitudes. Although there was no correlation between their at-sea distributions, there was a broad overlap between birds and fishing effort. Estimated bycatch rates for Tristan albatross and other Diomedea species in the South Atlantic, and the spatio-temporal overlap between birds and hooks, yield a predicted annual mortality of 471-554 birds, sufficient to cause population decreases of 3.6-4.3% per year. An index of bird × hook interactions (proportional density of birds multiplied by number of hooks by decadal period for each 5° square of longitude and latitude) indicated that 47% of annual interactions occurred in areas around Gough Island, and 11% and 15% of interactions in areas of the west and east Atlantic, respectively. There were also within seasonal differences in the key areas of overlap. The fishing fleets of Taiwan and Japan are likely to be responsible for most interactions based upon the reported magnitude of effort expended in the South Atlantic by these fleets. Ensuring that licensed fishing vessels within the Tristan da Cunha Exclusive Economic Zone (EEZ) operate using best-practise mitigation measures and with fisheries observer programs, could reduce the potential bycatch mortality of breeding Tristan albatrosses in this region by nearly one third. Thorough implementation of international agreements is required in areas of the high seas where most remaining interactions are predicted to occur.     

Modeling loggerhead sea turtle (Caretta caretta) interactions with US Mid-Atlantic bottom trawl gear for fish and scallops, 2005–2008

Interactions between sea turtles and northwestern Atlantic trawl fisheries are of global concern, and the National Marine Fisheries Service is considering expanding bycatch reduction regulations, including deployment of turtle excluder devices (TEDs). To inform bycatch mitigation strategies, the number of loggerhead sea turtle (Caretta caretta) interactions was estimated for US Mid-Atlantic bottom trawl fisheries for fish and scallops. A generalized additive model of interactions was developed using 1994–2008 Northeast Fisheries Observer Program data from trawl fisheries that were not required to deploy TEDs. Predicted loggerhead interaction rates were applied to 2005–2008 commercial fishing data to estimate the number of interactions for the trawl fleet. For trawl fisheries in which TEDs were required, an experimentally-determined TED exclusion rate (97%) was applied to estimate the number of loggerheads that were excluded by TEDs. Latitude, depth, and sea surface temperature (SST) were associated with the interaction rate. Average annual interactions for 2005–2008 were estimated at 292 (CV 0.13, 95% CI 221–369) loggerheads, with an additional 61 (CV 0.17, 95% CI 41–83) excluded by TEDs. The interaction rate was highest south of latitude 37°N in waters <50 m deep with SST >15 °C; interaction magnitude in terms of adult equivalents was highest at latitude 37–39°N, depth <50 m, and SST >15 °C. Predicted average annual loggerhead interactions decreased compared to 1996–2004, likely due to decreased commercial fishing effort in high-interaction areas. Additional sea turtle conservation measures can be informed by the high-interaction-rate and -magnitude areas identified through this analysis.     

Reducing longline bycatch: The larger the hook, the fewer the stingrays

Chondrichthyan populations in the Mediterranean Sea have been heavily affected by the impact of fishing activities. In the last two decades, even fishing gears that were traditionally considered highly selective, such as pelagic longlines, have been revealed to be responsible for the capture of many unwanted species. The pelagic stingray (Pteroplatytrygon violacea) is not an endangered nor a charismatic species, but it largely dominates longlines bycatch fractions.The aim of our study was to investigate the importance of three main variables, bait size, presence and type of light attractors, and hook size and shape, in the capture rate of pelagic stingrays. Ninety-seven longline experimental sets were run. Trials took place on nine vessels in the Strait of Sicily, central Mediterranean Sea, over a period of 3 years from 2005 to 2007. Results showed that the larger the J hook, the lower the stingray capture rate. Moreover, 16/0 circle hooks had a significantly lower number of stingrays captured per 1000 hooks than J hooks, up to ∼80%. Bait size, within the range of sizes assessed, and use of light attractors did not have significant effects on stingray catch rate. These results suggest that the adoption of large circle hooks by commercial and artisanal swordfish longlining may be a measure to reduce their environmental footprint.     

Pelagic longlines: A threat to sea turtles in the Equatorial Eastern Atlantic

Pelagic longlines are widely known to interact with several species of sea turtles, and there is an increasing concern about the by-catch of turtles in commercial fisheries and its impact on their populations. However, information on sea turtle by-catch in the South Atlantic Ocean is scarce, and there are no quantitative by-catch data available on olive ridleys for the Equatorial Eastern Atlantic. In this paper we analyze data collected by observers on board an Uruguayan long-liner targeting swordfish in two areas in the Equatorial Eastern Atlantic: off the Gulf of Guinea and north of Saint Helenaa Island. Specimens of Lepidochelys olivacea and Dermochelys coriacea were hooked or entangled in 26 longline sets. All registered interactions with olive ridleys took place off the The Gulf of Guinea, with captures ranging from 1 to 3 specimens in a single set. The captured specimens, though not measured directly, appeared to be juveniles. In addition, the examination of the stomach contents of one female mako shark showed dermal scutes, vertebrae and the complete head of a sea turtle identified as L. olivacea, allowing us to estimate its curved carapace length. In contrast, adult specimens of D. coriacea were caught in the two fishing areas. The capture of 10 individuals in a single set was recorded. Due to the high rate of sea turtle by-catch observed off the The Gulf of Guinea (1.02 ind/1000 hooks) conservation programs in the area should take into consideration the possible existence of a developmental and feeding area in this zone. Accordingly, longline fisheries in this area should be monitored and mitigation measures put in place to avoid or minimize damage to the pelagic phase of African populations of sea turtles.     

Increasing turtle strandings in the southeast United States: A complicating factor

Increased strandings of dead loggerhead sea turtles Caretta caretta on southeast US shores may be the result of increased fishing efficiency and improved recruitment of young turtles to the population. Possibly, the practice of discarding overboard large amounts of unwanted fish and biological material may provide a major energy resource for loggerhead sea turtles and crabs, which are also loggerhead food items. Our observations show that many dead loggerheads stranded on Cumberland Island had eaten man-caught food in addition to the expected diet of crabs and other bottom-dwelling animals. Consideration of alternative methods of handling the incidental fish catch while trawling for shrimp may be useful in reducing the problem of killing of sea turtles in shrimp trawls.     

Assessing the susceptibility of female black-footed albatross (Phoebastria nigripes) to longline fisheries during their post-breeding dispersal: an integrated approach

Albatross movements and foraging grounds during the post-breeding dispersal are poorly understood, despite their important conservation implications. We tracked four female black-footed albatrosses (Phoebastria nigripes) for 100 days during their summer (July-September, 1997-1999) post-breeding dispersal off California, and compared their movements to the distribution of fishing effort from the Japanese Eastern Pacific Ocean (EPO) longline fishery. The tracked birds foraged largely along the transition zone between the California Current and the Central Pacific Gyre, and spent 25, 24, and 51% of their time at sea within the 200-mile exclusive economic zones (EEZs) of the USA and Mexico, and the high seas (international waters) respectively. The satellite-tracked birds occupied subtropical waters (18-20 °C) targeted by longline fisheries for tuna (Thunnus spp.) and broad-bill swordfish (Xiphias gladius), and ranged disproportionately farther during daylight hours, when tuna fisheries operate. The available data suggest that albatrosses overlap temporally and spatially with longline fisheries in the northeast Pacific Ocean. However, this research cannot directly evaluate whether black-footed albatross bycatch occurs in these fisheries. The coarse temporal (monthly) and spatial (1°×1°) resolution of the fisheries data, and the dynamic nature of the fishing effort inhibited a fine-scale analysis of albatross overlap with longline fisheries. While we documented substantial spatial overlap between albatross distributions and the Japanese EPO longline fishing effort during the 1980s, we found no co-occurrence during the 1990s. This study illustrates the value of satellite telemetry to assess national conservation responsibilities, and to identify potential interactions of protected species with fisheries not currently monitored by observer programs. Furthermore, our results underscore the need to exercise caution when interpreting satellite telemetry data for conservation purposes, because of the highly dynamic nature of pelagic fisheries.     

Do circle hooks reduce the mortality of sea turtles in pelagic longlines? A review of recent experiments

Circle hooks have been proposed as a means of reducing the by-catch mortality of sea turtles in pelagic longline fisheries to sustainable levels. I examine the efficacy of circle hooks as a sea turtle conservation measure by examining the results of field trials conducted in the western North Atlantic, the Azores, the Gulf of Mexico, and Ecuador. These experiments employed more than a million and a half hooks between 2000 and 2004 and, in general, were well designed, conducted and analyzed. Four of five experiments demonstrated a significant reduction in capture rate and/or hooking location, indicating that circle hooks would reduce overall mortality. In one trial, however, circle hooks reduced catches of target species to such a degree that their use was impractical. I conclude, therefore, that circle hooks have the potential to reduce the mortality of sea turtles captured in many (but not all) pelagic longline fisheries, but that they should be field tested in a rigorous experiment before they are required in any fishery. Circle hooks will not reduce mortality rates of sea turtles in every pelagic longline fishery; each case needs to be tested before this measure is adopted. Circle hooks reduce turtle mortality because of their shape and size and the ways that these parameters interact with the size of turtles interacting with the fishery. Circle hooks may cause a reduction in turtle mortality by decreasing the incidence of hook ingestion as well as reducing capture rate, particularly for loggerhead sea turtles.     

The impact of pelagic longline fishing on the flesh-footed shearwater Puffinus carneipes in Eastern Australia

The flesh-footed shearwater (Puffinus carneipes) is a medium-sized seabird (ca. 700 g) that is incidentally killed during longline fishing operations. We examined the levels of bycatch in Australia’s Eastern Tuna and Billfish Fishery and developed a model to examine the impact of this fishery on the eastern Australian population of flesh-footed shearwaters, which breeds at only one site, Lord Howe Island. Observed bycatch rates for flesh-footed shearwaters were 0.378 birds/1000 hooks for night sets, and 0.945 birds/1000 hooks for day sets. The mean number of birds killed from 1998 to 2002 was estimated to be 1794-4486 birds per year, with the estimated total killed over this period ranging from 8972 to 18,490 birds. Models incorporating both density-independent and density-dependent scenarios were applied to levels of bycatch representative of that observed in the fishery. Density-independent scenarios showed that fishing mortality levels caused declines in the majority of simulated populations. In contrast, density-dependent scenarios produced populations that were more resilient to fishing mortalities. Although some modelling scenarios led to population growth, under most stochastic simulations median population halving and quasi-extinction times were less than 55 and 120 years, respectively. We conclude that the level of bycatch observed in the fishery is most likely unsustainable and threatens the survival of the Lord Howe Island population. This situation can be improved only with the development and implementation of mitigation measures that will halt or greatly reduce the level of bycatch currently observed. Improved knowledge on a range of demographic parameters for the species, combined with a clearer idea of the at-sea distribution of breeding and non-breeding shearwaters, will greatly assist in improving understanding and the management of this population.     

Seabird and longline interactions: effects of a bird-scaring streamer line and line shooter on the incidental capture of northern fulmars Fulmarus glacialis

Interactions between seabirds and longline fishing can cause incidental bird mortality and reduced gear efficiency. The potential for solving these problems by using a bird-scaring streamer line and a line shooter was investigated in commercial longlining in the northern Atlantic off the coast of Norway. We compared the bycatch rate of northern fulmars Fulmarus glacialis, the loss rate of baits to fulmars and the catch rates of fish target species among lines set with either of these mitigation measures, a combination of both and no mitigation measure. A total of 58,420 hooks were set in each of the four treatments. No birds were caught using the bird-scaring line alone and a single fulmar was caught when the bird-scaring line was used in combination with the line shooter. In contrast, 32 fulmars were caught in sets with no mitigation device and thirteen in sets with the line shooter alone. Losses of mackerel bait were reduced when the bird-scaring line was used, but not by using the line shooter alone. Longlines set with the line shooter reached 3 m depth 15% faster then lines set without the line shooter; beyond this depth sinking rates were similar (about 15 cm s⁻¹). Fish catch did not vary significantly among setting methods. These results should also be applicable to the bycatch of Fulmarus spp. in demersal longline fisheries worldwide.     

Potential impacts of emerging mahi-mahi fisheries on sea turtle and elasmobranch bycatch species

Mahi-mahi (Coryphaena hippurus) is a resilient pelagic species that could provide long-term highly productive fisheries. Using FAO data we document enormous increases (746%) in reported global mahi-mahi landings since 1950. Detailed mahi-mahi fisheries records are limited, but an observer program monitoring Costa Rica’s Pacific mahi-mahi pelagic longline fleet between 1999 and 2008 (n = 217 sets) provided a rare opportunity to quantify bycatch in these fisheries. Several sea turtles and sharks of global conservation concern were caught incidentally: olive ridley turtle (Lepidochelys olivacea; n = 1348, mean = 9.05 per 1000 hooks), silky shark (Carcharhinus falciformis; n = 402, mean = 2.96 per 1000 hooks), thresher sharks (Alopias sp.; n = 158, mean = 1.12 per 1000 hooks), green turtle (Chelonia mydas; n = 49, mean = 0.35 per 1000 hooks), and three other threatened sharks in small numbers. Pelagic stingray (Pteroplatytrygon violacea; a ray of low conservation concern) was also a common bycatch (n = 625, mean = 4.77 per 1000 hooks). Generalized linear models (GLMs) of catch rates showed increases in olive ridley turtles and decreases in mahi-mahi and silky sharks over the decade examined. The high hooking survival rates of olive ridley and green turtles in observed sets (95% and 96% respectively) suggest that widespread training of the fleet in careful gear removal and turtle release methods could be one effective bycatch mitigation strategy for these species. GLMs also provide evidence that closing the fishery during peak olive ridley nesting times (at least near nesting beaches), in combination with reduced gear soak times, could help minimize the fishery’s impacts on threatened bycatch species while still maintaining a productive fishery.     

Incidental catch of the loggerhead turtle Caretta caretta off the Balearic Islands (western Mediterranean)

A survey, which included questionnaires for fishermen and the placement of observers onboard fishing vessels, was conducted to assess turtle catch off the Balearic Islands. The survey focused on those fishing vessels whose base port was in the archipelago and, hence, the catch of South-eastern Spain longliners moving in summer to the archipelago was not considered. The fishermen's perception was that the stock of loggerhead turtles is declining in the archipelago and that fishing activities are at least partially responsible for this trend. The observer reports indicated that the figures produced by the interviewees for catch per unit effort (CPUE) were reliable. Therefore, on the basis of these figures we calculated a total catch of 373 (95% CI: 365-308) loggerheads for 2001. Most turtles were caught in lobster trammel nets (196; 95% CI: 269-123) or drifting longlines (102; 95% CI: 111-93). Although the CPUE was much lower for the former, total catch was greater because of a larger fleet. Moreover, most loggerheads caught in lobster trammel nets were found dead when nets were hauled in, while no immediate mortality was observed in individuals caught in drifting longlines. This observation highlights the threat of trammel nets to loggerhead turtle populations. The estimated impact of the catches on the turtle population depends on the origin of the individuals inhabiting the region, which is yet to be established.     

Estimates of sea turtle mortality from poaching and bycatch in Bahía Magdalena, Baja California Sur, Mexico

Bahia Magdalena on the Pacific coast of Baja California Sur, Mexico, is an important feeding and nursery ground for black turtles Chelonia mydas, loggerhead turtles Caretta caretta, olive ridley turtles Lepidochelys olivacea, and hawksbill turtles Eretmochelys imbricata. Despite international and national protection, sea turtles continue to be caught incidentally and hunted for consumption in large numbers. This study examines the mortality of sea turtles in Bahia Magdalena, focusing on (1) species distribution and number of carcasses found, (2) causes of death, (3) size frequency distribution and % juveniles in the catch, and (4) changes in average size over the past years. A total of 1945 turtle carcasses were found from April 2000 to July 2003 along beaches and in towns of the region with loggerhead (44.1%) and black turtles (36.9%) being the dominant species. Slaughter for human consumption was the primary cause of death of carcasses found in towns (95-100%), while carcasses on beaches mostly died of unknown causes (76-100%). Circumstantial evidence suggests however, that incidental bycatch was the main mortality cause on beaches. Black turtles suffered the highest consumption mortality overall (91%), followed by olive ridley (84%), hawksbill (83%) and loggerhead turtles (63%). Over 90% of all turtles found were juveniles or subadults. Carapace length of black turtles declined consistently over the sampling period, while that of loggerhead turtles increased. Our results strongly suggest that turtles are being taken at high and unsustainable rates; this may partially explain why the populations have not recovered despite widespread protection on nesting beaches.     

Canadian waters provide critical foraging habitat for leatherback sea turtles

From 1998-2005, we collected 851 geo-referenced records of leatherback turtles, Dermochelys coriacea, from a volunteer network of commercial fishers and tour boat operators in Atlantic Canada. These data provide new insight into the spatial and temporal distribution of leatherbacks in temperate northwest Atlantic waters. Patterns in sightings data were consistent with the results of concurrent satellite telemetry studies, revealing a broad distribution of leatherbacks on the Scotian Shelf throughout the foraging season, and regular occurrence in the southern Gulf of St. Lawrence in late summer and fall. Our results suggest inter-annual variation in leatherback abundance in Canadian waters, with reported sightings across all years peaking on August 5 (95% CI: July 25-August 15). Weekly mean area sea surface temperature (SST) had a significant effect on the number of leatherback sightings reported, independent of day of year, with each 1 °C rise in temperature increasing reported sightings by 12.5% (95% CI: 2.1-23.8%). Most turtles were reported inshore from the continental shelf break and mean SST associated with sightings was 16.6 °C (sd = 2.3 °C). Our findings suggest that Canadian waters support one of the highest summer and fall densities of leatherbacks in the North Atlantic, and should be considered critical foraging habitat for this endangered species. Conservation efforts must be broadened to address threats to leatherbacks in this area.     

Small cetacean captures in Peruvian artisanal fisheries: High despite protective legislation

We detail the first direct, at sea monitoring of small cetacean interactions with Peruvian artisanal drift gillnet and longline fisheries. A total of 253 small cetaceans were captured during 66 monitored fishing trips (Gillnet: 46 trips; Longline: 20 trips) from the port of Salaverry, northern Peru (8^o14′S, 78^o59′W) from March 2005 to July 2007. The most commonly captured species were common dolphins (Delphinus spp.) (47%), dusky dolphins (Lagenorhynchus obscurus) (29%), common bottlenose dolphins (Tursiops truncatus) (13%) and Burmeister’s porpoises (Phocoena spinipinnis) (6%). An estimated 95% of common dolphin bycatch was of long-beaked common dolphins (Delphinus capensis). Overall bycatch per unit effort for gillnet vessels (mean ± sd) was estimated to be 0.65 ± 0.41 animals.set⁻¹ (range 0.05-1.50) and overall catch (bycatch and harpoon) was 4.96 ± 3.33 animals.trip⁻¹ (range 0.33-13.33). Based upon total fishing effort for Salaverry we estimated the total annual average small cetacean bycatch by gillnet vessels as 2412 animals.year⁻¹ (95% CI 1092-4303) for 2002-2007. This work indicates that, in at least one Peruvian port, bycatch and harpooning of small cetaceans persist at high levels and on a regular basis, particularly in driftnet vessels, despite the existence since the mid-1990s of national legislation banning the capture of marine mammals and commerce in their products. It is concluded that the coast of Peru is likely still one of the world’s principal areas for concern regarding high small cetacean bycatch and there is clearly an urgent need to increase the geographic scope of observer effort to elucidate the full magnitude of this issue.     

Spatio-temporal trends of longline fishing effort in the Southern Ocean and implications for seabird bycatch

Longline fisheries have expanded throughout the world's oceans since major commercial distant-water pelagic fleets began fishing for tuna and tuna-like species in the early 1950s. Along with the more recent development and expansion of demersal longline fleets for species such as Patagonian toothfish, these vessels are a major source of mortality to several species of seabird. Vessels can set many thousands of baited hooks in a day across many kilometres of water. These waters are often used as foraging areas by wide-ranging seabirds. Attracted by baits and offal, the birds can be caught on the baited hooks and subsequently drown. To provide a greater understanding of the potential impact of the Southern Ocean's longline fleets on seabird populations, this paper describes the trends in longline effort of the major pelagic and demersal fisheries in southern waters. The total reported effort from all longline fleets south of 30°S has been well over 250 million hooks per year since the early 1990s. However the spatial and temporal distribution of this effort has not been constant. While effort from the Japanese pelagic distant-water longline fleet declined through the 1990s, the Taiwanese fleet expanded dramatically. Likewise demersal fishing for toothfish increased markedly during the mid-1990s. These fisheries, along with substantial illegal longline fisheries, may be placing the long-term viability of many Southern Ocean species of seabird in jeopardy.     

Post-breeding season distribution of black-footed and Laysan albatrosses satellite-tagged in Alaska: Inter-specific differences in spatial overlap with North Pacific fisheries

We integrated satellite-tracking data from black-footed albatrosses (Phoebastria nigripes; n = 7) and Laysan albatrosses captured in Alaska (Phoebastria immutabilis; n = 18) with data on fishing effort and distribution from commercial fisheries in the North Pacific in order to assess potential risk from bycatch. Albatrosses were satellite-tagged at-sea in the Central Aleutian Islands, Alaska, and tracked during the post-breeding season, July-October 2005 and 2006. In Alaskan waters, fishing effort occurred almost exclusively within continental shelf and slope waters. Potential fishery interaction for black-footed albatrosses, which most often frequented shelf-slope waters, was greatest with sablefish (Anoplopoma fimbria) longline and pot fisheries and with the Pacific halibut (Hippoglossus stenolepsis) longline fishery. In contrast, Laysan albatrosses spent as much time over oceanic waters beyond the continental shelf and slope, thereby overlapping less with fisheries in Alaska than black-footed albatrosses. Regionally, Laysan albatrosses had the greatest potential fishery interaction with the Atka mackerel (Pleurogrammus monopterygius) trawl fishery in the Western Aleutian Islands and the sablefish pot fishery in the Central Aleutian Islands. Black-footed albatrosses ranged further beyond Alaskan waters than Laysan albatrosses, overlapping west coast Canada fisheries and pelagic longline fisheries in the subarctic transition domain; Laysan albatrosses remained north of these pelagic fisheries. Due to inter-specific differences in oceanic distribution and habitat use, the overlap of fisheries with the post-breeding distribution of black-footed albatrosses is greater than that for Laysan albatrosses, highlighting inter-specific differences in potential vulnerability to bycatch and risk of population-level impacts from fisheries.     

An interview-based approach to assess marine mammal and sea turtle captures in artisanal fisheries

Recent case studies have highlighted high bycatch mortality of sea turtles and marine mammals in artisanal fisheries, but in most countries there are few data on artisanal fishing effort, catch, or bycatch. With artisanal fisheries comprising >95% of the world’s fishermen, this knowledge gap presents a major challenge to threatened species conservation and sustainable fisheries initiatives. We report on results from an intensive pilot study to evaluate whether interview surveys can be effective in assessing fishing effort and threatened species bycatch. Fisheries and bycatch data from interviews with >6100 fishermen in seven developing countries were collected in <1 year for approximately USD $47,000, indicating that this approach may rapidly yield coarse-level information over large areas at low cost. This effort provided the first fisheries characterizations for many areas and revealed the widespread nature of high bycatch in artisanal fisheries. Challenges to study design and implementation prevented quantitative estimation or spatial comparisons of bycatch during this pilot research phase, but results suggested that annual sea turtle bycatch may number at least in the low thousands of individuals per country. Annual odontocete bycatch may number at least in the low hundreds per country. Sirenian bycatch occurred in all study areas but was frequent only in West Africa. We discuss lessons learned from this survey effort and present a revised protocol for future interview-based bycatch assessments.