Shark bycatch and depredation in the U.S. Atlantic pelagic longline fishery

The non-target bycatch of sharks in pelagic longline (PLL) fisheries represents a potential source of compromise to shark populations worldwide. Moreover, shark bycatch and depredation (damage inflicted on gear, bait, and catch) complicates management of sharks and other species, and can undermine the operations and financial interests of the pelagic longline industry. Thus, deducing means to reduce shark interactions is in the best interest of multiple stakeholder groups. Prior to doing so, however, the extent, cause and effect of these interactions must be better understood. In this review we address or conduct the following in relation to the U.S. Atlantic, Gulf of Mexico and Caribbean PLL fishery: (1) U.S. management governing shark interactions in the Atlantic; (2) the primary species encountered and historical shark catch data associated with PLL fishing in the Atlantic; (3) a historical comparison of area-specific shark species catch records between the two primary sources of shark catch data in this fishery; (4) the conditions and dynamics that dictate shark interactions in this fishery, and potential means to reduce these interactions, and; (5) a synthesis of the estimated impacts of this fishery on shark populations relative to other fisheries in the Atlantic. As has been found in other PLL fisheries, the blue shark (Prionace glauca) is clearly the shark species most commonly encountered in this fishery in the Atlantic, and receives the majority of attention in this review. U.S. management areas with high relative shark species diversities had a greater divergence in historical shark species percent-compositions between data sources (Pelagic Observer Program versus mandatory pelagic Logbook databases); this complicates the ability to conclude which species are most impacted by PLL fishing in those areas. The current fishing effort by the U.S. PLL fleet is small compared to that of PLL fishing targeting sharks in the Atlantic by non-U.S. fleets, and therefore poses a comparatively lower threat to the stability of Atlantic shark populations. However, incidental shark encounters are inevitable in U.S. Atlantic PLL fishing operations. Thus, it is in the best interest of all stakeholders in the Atlantic to better understand the extent and conditions governing these interactions, and to explore methods to reduce both their occurrence and those aspects leading to higher rates of incidental shark mortality.     

Population growth rates of reef sharks with and without fishing on the great barrier reef: robust estimation with multiple models

Overfishing of sharks is a global concern, with increasing numbers of species threatened by overfishing. For many sharks, both catch rates and underwater visual surveys have been criticized as indices of abundance. In this context, estimation of population trends using individual demographic rates provides an important alternative means of assessing population status. However, such estimates involve uncertainties that must be appropriately characterized to credibly and effectively inform conservation efforts and management. Incorporating uncertainties into population assessment is especially important when key demographic rates are obtained via indirect methods, as is often the case for mortality rates of marine organisms subject to fishing. Here, focusing on two reef shark species on the Great Barrier Reef, Australia, we estimated natural and total mortality rates using several indirect methods, and determined the population growth rates resulting from each. We used bootstrapping to quantify the uncertainty associated with each estimate, and to evaluate the extent of agreement between estimates. Multiple models produced highly concordant natural and total mortality rates, and associated population growth rates, once the uncertainties associated with the individual estimates were taken into account. Consensus estimates of natural and total population growth across multiple models support the hypothesis that these species are declining rapidly due to fishing, in contrast to conclusions previously drawn from catch rate trends. Moreover, quantitative projections of abundance differences on fished versus unfished reefs, based on the population growth rate estimates, are comparable to those found in previous studies using underwater visual surveys. These findings appear to justify management actions to substantially reduce the fishing mortality of reef sharks. They also highlight the potential utility of rigorously characterizing uncertainty, and applying multiple assessment methods, to obtain robust estimates of population trends in species threatened by overfishing.     

Elasmobranchs in southern Indonesian fisheries: the fisheries, the status of the stocks and management options

The biology of elasmobranchs makes them very vulnerable to fishing pressure and there is increasing international concern over their exploitation. In northern Australia the stocks of some species may be shared with those in southern Indonesia. Indonesia has the highest landings of elasmobranchs worldwide (>100,000 t p.a.) and millions of Indonesian artisanal fishers rely heavily on elasmobranchs taken in target fisheries. They are also taken by industrial trawlers and as bycatch in pelagic tuna fisheries. This paper, resulting from a collaborative project between Australia and Indonesia, summarises the elasmobranch fisheries; the characteristics of the fisheries are outlined, the status of the stocks are assessed, and management options described and discussed. The project focussed on representative markets and fish landing sites in southern Indonesia from 2001 to 2005. Data were from market surveys, the records of the Indonesian Directorate General of Capture Fisheries, and from research cruises. Data from the ongoing tuna monitoring programme showed that shark bycatch from the tuna fleets forms about 11% of shark landings in Indonesia. Yield per recruit and related analyses were used to integrate biological information to indicate the productivity of each species to allow for management policy options and constraints. Research cruise data show that catch rates of elasmobranchs in the Java Sea declined by at least one order of magnitude between 1976 and 1997. The results indicate strongly that many of the shark and ray species in Indonesia are overfished and that the most effective management strategy may need to involve capacity control, such as licencing, gear restrictions and catch limits, together with controls on the fin trade.     

Geographical variability in life‐history traits of a midslope dogfish: the brier shark Deania calcea

Deania calcea (n = 420) were collected from the catch of deep‐water trawlers in the southern and eastern scalefish and shark fishery in southern Australia during the years 2008–2011. The total length (L_T) range varied between sexes, females being larger (n = 264; 280–1530 mm) than males (n = 156; 310–921 mm). The reproductive cycle in this population is non‐continuous and asynchronous. The estimated L_T at which 50% of males are mature is 807 mm and is 914 mm for females. Populations of D. calcea in higher latitudes appear to mature at a larger size than conspecifics in lower latitudes, in both the northern and southern hemispheres. Litters ranged from three to 10 embryos with a 1:1 sex ratio, but litter size does not increase with maternal L_T. Deania calcea shows geographical variability in its biological parameters and gathering information on life‐history traits of populations is vital to understand the trade‐offs made by this species in response to environmental conditions and to predict intraspecific spatial differences. Such information is a basis for specific spatial management to protect populations from excessive fishing.     

Preliminary data on elasmobranch gillnet fishery in the Gulf of Gabès,Tunisia

Elasmobranchs are an important catch component in Tunisian artisanal fisheries. Generally, species‐specific information is largely unavailable for artisanal fisheries; an increase in knowledge thereof is essential to ensure proper management of these species. The study analyzed the gillnet fishery elasmobranch catches in the Gulf of Gabès, whereby 45 fishing trips were conducted from April to June 2007 and 2008 for the capture of a total of six species: three Rajiformes and three Carchariniformes. Rhinobatos cemiculus was the most important species (52%; 4.588 ind km^?2 net per day). Among shark species, Mustelus mustelus was the most important (66.8%; 2.21 ind km^?2 net per day). Discards represented 6.87% of total catch in weight and 14.28% in number of specimens caught. Size composition of captures varied by species, but usually mature, mainly gravid females were abundant. Further investigations are needed to obtain more information on such fragile species for the development of protective measures.     

Occurrence and biological characteristics of broadnose sevengill sharks (Notorynchus cepedianus) in Pacific Northwest coastal estuaries

The broadnose sevengill shark (Notorynchus cepedianus) is a high-order marine predator distributed worldwide in shallow coastal waters of temperate seas. Recent reports have suggested it may be a prevalent component of Pacific Northwest coastal estuarine communities, although biological characteristics of the shark population remain undocumented despite growing interest in recreational harvest of the species. Longline sampling was conducted in Willapa Bay and Grays Harbor, Washington, USA seasonally during 2003–2006 to collect sevengill shark size, maturity, and sex ratio data, and establish some baseline catch rate information. Sevengill sharks were collected on 65% of longline sets and catches were composed of subadult and mature individuals (122–283 cm TL) of both sexes. Most male sevengill sharks were large sexually mature adults, based on external clasper calcification levels, whereas most comparably sized females were considered subadults, based on literature-based size-at–maturity estimates. Neonates and young sharks <120 cm were not collected, nor have they been reported in other historic estuary sampling efforts. Sex ratios were skewed toward males in Willapa Bay and suggest some degree of sexual segregation for the species, as has been shown for populations elsewhere. We suggest sevengill sharks are a largely ignored but potentially important predator in Pacific Northwest estuaries. This study therefore provides some of the first, basic information for guiding management decisions associated with a late-maturing, slow-growing shark species in these coastal habitats.     

A plan for fisheries management in the lakes drained by the Oulujoki river

Freshwater fishery management is treated as a dynamic system comprising environment protection and improvement, fishing, fishery resources allocation, fish stocking programs and marketing policy. The aims of the plan are to increase the economic value of the catch and to protect the professional fishery. Fisheries statistics, catch per unit effort data and other material were collected during 1972–1976. The total allowable catch (TAC) for the most important fish species was estimated with MSY and population analysis models. The results of fish stockings were studied by tagging and population analysis calculations. Fishing of vendace and non-valuable species (perch, roach, smelt) can be increased, but the fishing pressure on other species should not be raised above the present level. Restrictions on whitefish fishing are needed in some areas. A balanced multispecies fishery is desirable, and suggestions are given for the composition of the fishing gear. Fish stocking can make possible a larger and more valuable catch, but at present its profitability is rather low. The stocking results are strongly affected by the fishery and the gear composition.     

北大西洋大青鲨种群统计分析

大青鲨是金枪鱼延绳钓渔业中最主要的兼捕鱼种,在海洋食物网中属于顶端物种,在海洋生态系统中处于重要地位.由于数据限制,传统的资源评估方法很难准确描述大青鲨的资源动态.本研究基于大青鲨的生活史参数,应用种群统计分析法评估大青鲨的种群参数和资源状态,并探讨了内禀增长率为0时对应的临界捕捞死亡系数F_c与开捕年龄t_c的关系.结果表明： 未开发状态下,大青鲨存活率为0.719～0.820;大青鲨的内在瞬时增长率(r₀)为0.250～0.381,种群倍增时间(t_x2)为1.819～2.773年,种群的净繁殖力(R₀)为6.600～22.255,世代间期时间(G)为8.498～〖JP2〗10.162年,种群资源状态良好.生活史参数的敏感性检验显示,大青鲨初始年龄的自然死亡系数、种群性成熟年龄及寿命的不确定性对种群统计参数的意义影响不大;临界捕捞死亡系数伴随开捕年龄的增大而增大,当t_c≥5时,F_c值与t_c无显著相关关系.     

Small-Scale Spatial Variation in Population Dynamics and Fishermen Response in a Coastal Marine Fishery

A major challenge for small-scale fisheries management is high spatial variability in the demography and life history characteristics of target species. Implementation of local management actions that can reduce overfishing and maximize yields requires quantifying ecological heterogeneity at small spatial scales and is therefore limited by available resources and data. Collaborative fisheries research (CFR) is an effective means to collect essential fishery information at local scales, and to develop the social, technical, and logistical framework for fisheries management innovation. We used a CFR approach with fishing partners to collect and analyze geographically precise demographic information for grass rockfish (Sebastes rastrelliger), a sedentary, nearshore species harvested in the live fish fishery on the West Coast of the USA. Data were used to estimate geographically distinct growth rates, ages, mortality, and length frequency distributions in two environmental subregions of the Santa Barbara Channel, CA, USA. Results indicated the existence of two subpopulations; one located in the relatively cold, high productivity western Channel, and another in the relatively warm, low productivity eastern Channel. We parameterized yield per recruit models, the results of which suggested nearly twice as much yield per recruit in the high productivity subregion relative to the low productivity subregion. The spatial distribution of fishing in the two environmental subregions demonstrated a similar pattern to the yield per recruit outputs with greater landings, effort, and catch per unit effort in the high productivity subregion relative to the low productivity subregion. Understanding how spatial variability in stock dynamics translates to variability in fishery yield and distribution of effort is important to developing management plans that maximize fishing opportunities and conservation benefits at local scales.     

The shark assemblage at French Frigate Shoals atoll, Hawai'i: species composition, abundance and habitat use

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook hours of soak time. A total of 221 sharks from 7 species were captured, among which Galapagos (Carcharhinus galapagensis, 36.2%), gray reef (Carcharhinus amblyrhynchos, 25.8%) and tiger (Galeocerdo cuvier, 20.4%) sharks were numerically dominant. A lack of blacktip reef sharks (Carcharhinus melanopterus) distinguished the FFS shark assemblage from those at many other atolls in the Indo-Pacific. Compared to prior underwater visual survey estimates, longline methods more accurately represented species abundance and composition for the majority of shark species. Sharks were significantly less abundant in the shallow lagoon than adjacent habitats. Recaptures of Galapagos sharks provided the first empirical estimate of population size for any Galapagos shark population. The overall recapture rate was 5.4%. Multiple closed population models were evaluated, with Chao M(h) ranking best in model performance and yielding a population estimate of 668 sharks with 95% confidence intervals ranging from 289-1720. Low shark abundance in the shallow lagoon habitats suggests removal of a small number of sharks from the immediate vicinity of lagoonal islets may reduce short-term predation on endangered monk seal (Monachus schauinslandi) pups, but considerable fishing effort would be required to catch even a small number of sharks. Additional data on long-term movements and habitat use of sharks at FFS are required to better assess the likely ecological impacts of shark culling.     

A matter of size: the population structure of the smallest known living shark,Etmopterus perryi (Springer & Burgess, 1985), from deep waters off the Colombian Caribbean coast

The dwarf lanternshark (Etmopterus perryi) is the smallest known described shark, and practically no information has been available on this species since first described in the mid-1980s. Therefore, the aim of this work is to describe, for the first time, the population structure regarding dwarf lanternshark in the Colombian Caribbean Sea. During deep-water research surveys conducted along the Colombian Caribbean coast, 87 stations were sampled using the swept area method. A total of 153 dwarf lanternshark individuals were caught in depths ranging from 230 to 530 m. This information was used to describe the size structures, morphological measurements including length-at-weight relationship, length at maturity in females and the spatial distribution of mean length and biomass of the species. The lengths of individuals ranged from 78.02 to 289.00 mm total length (TL), which is a new record of maximum length for this species. The spatial distribution of mean lengths and biomass distributions show high abundances and high relative mean lengths in the northeast area off Santa Marta and the area northwest of Riohacha. The mean biomass density in the whole prospected area was 5.52 kg km⁻². Length at 50% maturity in females was estimated in 203 mm TL (95% C.I. : 190–214 mm). Deep-water elasmobranch species, such as the dwarf lantern shark, are expected to show extremely low resilience to fishing exploitation, even when they are not targeted by commercial fishing. Therefore, the information reported in this study can serve as a baseline upon which management measurements can be proposed for the conservation of this shark species.     

Biology and fishery of the lobster Panulirus gracilis in Playa Lagarto, Guanacaste, Costa Rica

Panulirus gracilis is a high valuable lobster species with considerable captures along the tropical Pacific coast. In this study, I present some biological and fishery parameters described after a sample of 843 lobsters, landed in Playa Lagarto from November 2007 to October 2008. From landing records, a total of 74.9% of lobsters were below the minimum legal catch size (80 mm CL). Carapace lengths were in the range of 42.8 and 143.6 mm for males and 115 and 35.8 mm for females. The size structure showed a wide overlapping of population segments, and a trend to increase with depth, where lung diving and "hooka" diving operations take place. Sex ratio was 1.36 M:H. The relationship between weight and LC revealed that females are heavier than males of the same size, and this difference was significant (p < 0.05). The von Bertalanffy growth parameters for males and females respectively (K = 0.45-0.38, LC(infinity) = 166.9-121.7) showed accelerated growth compared to other species. Males observed a higher growth rate than females. Furthermore, natural mortality (M), total mortality (Z) and fishing mortality (F) was higher in males (0.49-2.34-1.92) than in females (0.47-1.82-1.42). Recruitment was continuous for both sexes during the year, with an elevated intensity of 18.5% in July. Under the current fishing regime the population could be at risk of collapse, as indicated by the high exploitation rate (E) 0.80     

Identification of factors influencing shark catch and mortality in the Marshall Islands tuna longline fishery and management implications

Recent average annual catches of sharks by tuna longline vessels fishing in the Republic of the Marshall Islands (RMI) are estimated to be between 1583 and 2274 t. Although 22 shark species have been recorded by the observer programme for this fishery, 80% of the annual catch comprises only five species: blue shark Prionace glauca, silky shark Carcharhinus falciformis, bigeye thresher shark Alopias superciliosus, pelagic thresher shark Alopias pelagicus and oceanic whitetip shark Carcharhinus longimanus. Wire leaders (i.e. branch lines or traces) were also used by nearly all observed vessels. Generalized additive model (GAM)-based analyses of catch rates indicated that P. glauca and A. superciliosus are caught in higher numbers when vessels fish in relatively cooler waters, at night, close to the full moon, when the 27° C thermocline is close to the surface and during El Ni?o conditions. In contrast, C. falciformis, A. pelagicus and C. longimanus are caught in higher numbers when shark lines are used (all three species) or hooks are set at a shallow depth (A. pelagicus and C. longimanus and, also, P. glauca). These findings are generally consistent with current knowledge of these species' habitat preferences, movement and distribution. The results of these analyses were combined with information pertaining to shark condition and fate upon capture to compare the likely effectiveness of a range of potential measures for reducing shark mortality in the longline fishery. Of the options considered, the most effective would be to combine measures that reduce the catch rate (e.g. restrictions on the use of wire leaders, shark baits and shark lines) with measures that increase survival rates after post-capture release (e.g. finning bans).     

The need for conservation and management of Philippine coral reefs

Synopsis The biological diversity and productivity of Philippine coral reefs are threatened by siltation, destructive fishing methods, coral and shell collecting and overfishing. Destructive fishing includes: the widespread, illegal use of explosives; poisons such as sodium cyanide; muro-ami and kayakas fishing; and trawling. The recent decline in catch rates threatens the livelihood of 700 000 near-shore subsistence fishermen who catch 55% of the total landings. The new government under Corazon Aquino wishes to protect the marine environment through the creation of a viable marine conservation management plan, enforcement of existing laws and through cooperation between government, non-government and international agencies to provide education and research. The Department of Agriculture, which has the authority for fisheries, has designated the International Marinelife Alliance as the lead non-government agency involved with fund raising, net-training and finding alternatives to destructive fishing methods.This essay addresses the societal relationships of village fishery to government, aid organizations, and science. Vadim Vladykov always maintained close relationship with fishermen and devoted over a year of his life to helping develop fisheries in Iran.     

Fisheries, management and conservation of the whale shark Rhincodon typus in Taiwan

The Taiwanese government introduced a catch-and-report system for the whale shark Rhincodon typus in 2001, and in the following year limited the total allowable catch (TAC) to 80 individuals. This limit was reduced over the following years, reaching a low of 30 individuals in 2007. In November 2007, a comprehensive ban on R. typus fishing came into effect and protection measures were adopted for the species. This study measured and recorded the total length (L(T) ), body mass and sex of 810 R. typus, using fisheries and other released data for the period 1995-2008. The mean L(T) of individuals caught from June to October was smaller than that for individuals caught from November to May. Mean annual catches in set nets were higher in south-western Taiwan than in other regions of Taiwan. The sex ratio showed that males were caught more frequently than females in Taiwanese waters, indicating sex segregation. For the first time, the stock structure, conservation and management regulation of R. typus in the north-west Pacific Ocean have been reviewed. The results provide a useful resource for future assessment of the possible development of R. typus ecotourism in Taiwan.     

Eating catch of the day: the diet of porbeagle shark Lamna nasus (Bonnaterre 1788) based on stomach content analysis,and the interaction with trawl fisheries in the south-western Atlantic (52° S–56° S)

This work examined the diet of the porbeagle shark Lamna nasus in the south-west Atlantic Ocean (SWAO, Argentina, 52° S–56° S) by analysing the stomach content information obtained by scientific observers who sampled specimens captured as by-catch on-board commercial fishing vessels from 2010 to 2020. A total of 148 fishing sites were analysed, in which the estimated catch was composed mainly of hoki Macruronus magellanicus (56.00%) and southern blue whiting Micromesistius australis (33.13%). From 413 porbeagle sharks sampled (292 females and 121 males) ranging from 71 to 241 cm total length (L_T) (mean: 179.76 ± 26.74 cm), 310 (75.06%) contained food in the stomachs. The forage fish were mainly hoki M. magellanicus (23.53%) and southern blue whiting M. australis (19.05%), followed by the Patagonian sprat Sprattus fuegensis (4.48%) and nototheniids (1.4%). Cephalopods and crustaceans accounted for 10% of the diet. The estimated trophic level was 4.35. Generalized linear models revealed that the consumption of hoki M. magellanicus and southern blue whiting M. australis increased with the L_T of the porbeagle shark. Moreover, smaller porbeagle sharks preyed upon both small and large teleost fish, whereas larger porbeagle sharks predated exclusively upon large fish. The diet of porbeagle shark involved interactions with fisheries as it fed upon the fish species that constituted the main catch in the analysed fishing sites, as well as the main catches of the austral trawl fisheries. The ecological role of porbeagle shark observed in the SWAO exposed implications for fisheries management from a multispecies perspective.     

Global estimates of shark catches using trade records from commercial markets

Despite growing concerns about overexploitation of sharks, lack of accurate, species-specific harvest data often hampers quantitative stock assessment. In such cases, trade studies can provide insights into exploitation unavailable from traditional monitoring. We applied Bayesian statistical methods to trade data in combination with genetic identification to estimate by species, the annual number of globally traded shark fins, the most commercially valuable product from a group of species often unrecorded in harvest statistics. Our results provide the first fishery-independent estimate of the scale of shark catches worldwide and indicate that shark biomass in the fin trade is three to four times higher than shark catch figures reported in the only global data base. Comparison of our estimates to approximated stock assessment reference points for one of the most commonly traded species, blue shark, suggests that current trade volumes in numbers of sharks are close to or possibly exceeding the maximum sustainable yield levels.     

Catch composition and aspects of the biology of sharks caught by Thai commercial fisheries in the Andaman Sea

Catch composition, landing patterns and biological aspects of sharks caught by commercial fishing fleet operating in the Andaman Sea were recorded from landing sites in Ranong province of Thailand over a period of 1 year. Of the 64 species previously reported in the existing Thailand checklist, only 17 species were recorded in this study. Shark landings from the Andaman Sea appear now to be dominated largely by bamboo sharks Chiloscyllium spp. (Hemiscylliidae), which contribute c. 65% of the total number of sharks recorded. The carcharhinid sharks comprised c. 30·5% to the total catch, while the remaining c. 4·5% of landings comprised sharks from the families Squalidae, Stegostomatidae, Sphyrnidae and Triakidae. The catch composition is remarkably different from the previous landing survey in 2004, in that the current study found noticeable declines in landings of slow‐growing, late‐ maturing and low‐fecundity species (especially sphyrnid and carcharhinid species). The absences of many species and changes in life‐stage composition suggest that the populations of these groups may be close to collapse. The results from this study emphasize the urgency for additional research and monitoring efforts and also the need for management incentives in order to manage shark fisheries effectively in the Andaman Sea.     

Catch and discards from experimental trawl and longline fishing in the deep water of the Rockall Trough

Comparative bottom trawl and longline surveys were carried out on two chartered commercial fishing vessels in the deep waters (350-1300 m) of the Rockall Trough, an area subjected to heavy commercial exploitation. The species composition, catch rates and length distributions from each survey were very different and reflected the fundamental difference in the two types of fishing operations. Bottom-trawled catches produced greater species diversity and higher discard rates. Longline catches produced larger specimens of teleost fish and were dominated by squalid shark. Trawl discards, expressed as kgs of discards per tonne of roundnose grenadier Coryphaenoides rupestris landed, were calculated for a broad range of the most abundant species taken in the catch. First estimates of total international discarding from deep-water trawling operations in the Rockall Trough area (7530 tonnes; 26.5 million individuals) were made by raising the discard rates using international grenadier landings for 1995. The outlook for the continued exploitation of the deep-water fish resource in the Rockall Trough and possible management options are discussed.     

Effects of fishing methods on deep water shark species caught as by-catch off southern Portugal

Deep water sharks are commonly caught as by-catch of longlines targeting bony fishes and trawlers targeting crustaceans in deep water off the southern Portuguese coast. Due to low or no commercial value, these species are most of the times discarded at sea, with only the larger specimens of some species commercialized at very low prices. In this study we present size distributions, maturity distributions, and sex ratios of 2,138 specimens belonging to four different species, namely the lantern sharks Etmopterus pusillus and Etmopterus spinax and the catsharks Galeus melastomus and Galeus atlanticus, caught with these two gears. Trawls generally caught smaller-sized specimens, in a wider length range than longlines. Trawls caught mostly immature specimens of all species, namely 83.7% immature of E. pusillus, 84.3% of E. spinax, 89.5% of G. melastomus, and 95.5% of G. atlanticus, while longlines caught mostly immature E. pusillus (69.2%) and G. melastomus (78.6%) and mostly mature E. spinax (88.2%) and G. atlanticus (87.2%). Trawls tended to catch more males than females of all species except E. spinax, while longlines caught more females than males of E. spinax and G. melastomus and more males than females of the other two species. The main conclusion of this work is that trawls are catching smaller-sized and mostly immature specimens when compared to longlines, meaning that they are probably having a more detrimental effect on these shark populations. The data presented here have significant implications for the conservation of these shark populations since sizes, sexes, and the immature and mature components of the populations are being affected differently by these two fishing gears. Guest editors: J. Davenport, G. Burnell, T. Cross, M. Emmerson, R. McAllen, R. Ramsay & E. Rogan Challenges to Marine Ecosystems