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Alifa Bintha Haque Nidhi Gloria D'Costa Mahi Washim Amit Robert Baroi Nazia Hossain Mashrur Hafiz Sumaiya Rahman Karabi Farhana Biswas 《水产资源保护:海洋与淡水生态系统》2021,31(6):1392-1409
- Devil rays (Mobula spp.) are globally threatened cartilaginous fishes that have attracted global conservation concern owing to their high extinction risk and lack of protection in many countries. Limited resources and data on threatened marine species, including devil rays, impede conservation actions, particularly in developing countries, many of which have high biodiversity.
- Devil ray catch is a component of artisanal fisheries in Bangladesh, but data on their fisheries and trade are limited. To characterize devil ray fishing practices, fishers’ perception and trade, 230 fishers and traders were interviewed between 4 June 2018 and 22 June 2019, in four areas of south-east Bangladesh. Catch data were also opportunistically collected at landing sites.
- Six devil ray species were documented, caught in an array of gill nets, set-bag nets and longlines. All interviewed fishers reported life-long devil ray bycatch in some numbers, and also noted a decline in catch over the last decade. Bottom trawling, increased bycatch levels, increased demand for devil ray products and, in some cases, ecosystem changes were identified by fishers as threats to devil ray populations.
- Unregulated and undocumented trade and retained bycatch, especially by gill nets and set-bag nets, are fuelled by local consumption of devil ray meat and international trade in meat and gill rakers. Compliance with international trade control treaties for all Mobula spp. or the Bangladeshi law protecting Mobula mobular was low, with the majority of fishers (87%, n = 174) unaware of their existence.
- To manage devil ray fisheries, and prevent possible population declines, we propose a combination of legally enforced gear modifications, and catch and trade control through community-owned implementation strategies. Additionally, we propose the simultaneous implementation of inclusive, community-based awareness and stewardship projects in conjunction with a coast-wide ray monitoring programme. Finally, we emphasize that more research and action rooted in a sustainable fishery model is urgently needed to protect Bangladeshi devil ray populations.
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- Tuna fisheries are among the largest and most valuable fisheries in the world, but most interact with many non-target species, including several of high conservation importance. The spinetail devil ray (Mobula mobular) – listed as ‘Endangered’ on the IUCN Red List of Threatened Species – is a commonly discarded bycatch species, particularly in the eastern Pacific Ocean, yet insufficient data exist to undertake a traditional population assessment.
- A new ecological risk assessment approach designed for data-limited settings – Ecological Assessment of the Sustainable Impacts of Fisheries (EASI-Fish) – was used to reconstruct the historical vulnerability status of M. mobular and to simulate potential changes in its status under 45 hypothetical conservation and management measures. These involved various temporal closures of the eastern Pacific Ocean tuna fishery, decreasing post-capture mortality by improved handling and release practices, and combinations of the two.
- The species was classified as ‘Least Vulnerable’ between 1979 and 1993, but became ‘Most Vulnerable’ from 1994, which coincided with a rapid spatial expansion of the industrial purse-seine fishery, and especially from 2011 following the rapid increase in the number of sets made on floating objects. Simulating the conservation and management measures in place in 2018 revealed that 31 of the 45 scenarios resulted in a change in classification of the species to ‘Least Vulnerable’, which primarily involved a reduction of post-capture mortality by as little as 20%.
- It is fortuitous in that education of fishers to implement appropriate best handling and release practices is simpler, more rapid and more cost-effective than the implementation of fishery closures or gear modifications, which can be expensive and complex to implement and monitor and will probably result in substantial reduction in the catches of target species.
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Joanna L. Harris Peter K. McGregor Yvonne Oates Guy M. W. Stevens 《水产资源保护:海洋与淡水生态系统》2020,30(8):1649-1664
- Reef manta rays (Mobula alfredi) are one of the ocean's largest and most charismatic species. Pressure from targeted and bycatch fisheries coupled with their conservative life‐history traits including slow growth, late maturity, and low fecundity has led to catastrophic declines of the global population. The species is now listed as Vulnerable to Extinction on IUCN Red List of Threatened Species.
- The global M. alfredi population is widely distributed in highly fragmented subpopulations. The Maldives supports the world's largest known subpopulation that undergoes seasonal migrations which are thought to be linked to peaks in ocean productivity induced by the South Asian Monsoon. Although the species is protected from targeted fisheries in the region, increasing pressures from habitat degradation and unsustainable tourism activities mean their effective conservation relies upon knowledge of the species' habitat use, seasonal distribution, and the environmental influences on such movements.
- Photo‐ID sighting records collected between 2005 and 2017 were used to identify key aggregation sites throughout the archipelago, and multiple linear regression and prediction analysis identified the environmental variables affecting variations in the intra‐annual sighting frequency of M. alfredi.
- Mobula alfredi were recorded at 273 different sites, 48 of which, with >100 sightings at each, were classified as key areas of habitat use. South‐west monsoon winds and chlorophyll‐a concentration predominantly affected the monthly percentage of M. alfredi sighted on the down‐current side of the atolls.
- In a country where climate change and touristic pressure are increasingly threatening this species and its habitat, the identification of key areas of habitat use and temporal changes in the use of these sites highlight the areas that should be prioritized for protection enabling more effective conservation management.
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Hector M. Guzman Roberto Cipriani Angel J. Vega Jorge Manuel Morales‐Saldaa 《水产资源保护:海洋与淡水生态系统》2020,30(2):315-330
- In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
- To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
- In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
- It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.
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Leontine Baje Andrew Chin William T. White Colin A. Simpfendorfer 《水产资源保护:海洋与淡水生态系统》2021,31(11):3100-3110
- One-third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery.
- Eight species were classified to be at low risk, 28 species were at medium risk while three species – Rhynchobatus palpebratus (eyebrow wedgefish), Carcharhinus coatesi (Australian blackspot shark) and Maculabatis astra (blackspotted whipray), all endemic to New Guinea and northern Australia – faced the highest level of risk from the fishery at current fishing levels.
- There is potential for more vessels to enter the fishery in future, which is likely to elevate the risk for a greater proportion of elasmobranch species. Ongoing monitoring of bycatch levels, supported by biological and ecological studies on frequently caught species, is required to assess and manage risk in the future.
- The development and use of trawl excluder devices or bycatch reduction devices in this fishery have the potential to reduce bycatch levels and reduce risk levels.
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Donald A. Croll Heidi Dewar Nicholas K. Dulvy Daniel Fernando Malcolm P. Francis Felipe Galván‐Magaña Martin Hall Shawn Heinrichs Andrea Marshall Douglas Mccauley Kelly M. Newton Giuseppe Notarbartolo‐Di‐Sciara Mary O'Malley John O'Sullivan Marloes Poortvliet Marlon Roman Guy Stevens Bernie R. Tershy William T. White 《水产资源保护:海洋与淡水生态系统》2016,26(3):562-575
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Carlos Egberto Rodrigues Júnior Sandro Natal Daniel Diego Galetti Martins Diogo Teruo Hashimoto Fausto Foresti Fabio Porto‐Foresti 《水产资源保护:海洋与淡水生态系统》2020,30(6):1251-1254
- Billfish are oceanic pelagic species that are often caught by tuna fleets and are of great interest for sport fishing. Two species of billfish have specific legislation prohibiting their marketing and export in Brazil.
- DNA barcoding is a universal system of molecular identification based on a sequence of mitochondrial DNA cytochrome oxidase subunit I (COI), which serves as a diagnostic genomic marker in each species.
- The barcode DNA technique was used to identify billfish marketed in the second largest fishing warehouse in Latin America, the CEAGESP (Companhia de Entrepostos e Armazéns Gerais de São Paulo), located in São Paulo, Brazil. Seventy‐nine samples of billfish were collected during three inspection visits carried out by Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis.
- After DNA sequencing, 70 samples (88.60%) were identified to the species level; 21 (30.00%) were identified as Xiphias gladius, 43 (61.42%) as Istiophorus platypterus and six (8.57%) as Kajikia albida. The sale of this latter species is prohibited in Brazil and it is considered Vulnerable on the list of endangered species of the IUCN and in the official list of species of endangered Fauna – Fish and Aquatic Invertebrates.
- Molecular analyses proved to be very efficient at uncovering irregularities in the identification of the white marlin (K. albida), which was traded illegally in CEAGESP, demonstrating the ineffectiveness of the current monitoring techniques used and emphasizing the need for the adoption of better public policies for the conservation of the species.
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- This study aimed to determine biological and distributional aspects of deep-sea giant isopods Bathynomus giganteus and Bathynomus miyarei to assess their extinction risk.
- Bathynomus giganteus (663 specimens) and B. miyarei (649 specimens) were collected during five research cruises involving 265 h of sampling effort during 32 fishing operations of circular pots, baited traps, ranging from 400 and 1,000 m deep, between 26 and 29°S adjacent to the Brazilian coast.
- A trend towards larger, sexually mature animals in shallower regions was observed for both species, and depth was the most important environmental variable influencing the animals’ distribution.
- Bathynomus giganteus were collected between 600 m and 1,000 m depth, while the highest densities of B. miyarei were at shallower depths, between 400 and 600 m.
- The sex ratio was equal for both B. giganteus and B. miyarei for different seasons, latitudes and bathymetries.
- The sexual maturity of B. giganteus was estimated at 340–345 mm total length for males and between 280–290 mm for females. Bathynomus miyarei males’ sexual maturity was estimated in the 225–230 mm size class.
- Bathynomus giganteus showed reproductive activity throughout the year.
- The longevity of B. giganteus was estimated at 6 years for males and 7.7 years for females. The longevity of B. miyarei was estimated at 9 years for males and 6 years for females.
- Extinction risk assessment for B. giganteus, which has a greater latitudinal and bathymetric distribution, was evaluated as Least Concern. However, B. miyarei was evaluated in the Data Deficient category.
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Guillain Estivals Fabrice Duponchelle Uwe Rmer Carmen García‐Dvila Etienne Airola Margot Delglise Jean‐Franois Renno 《水产资源保护:海洋与淡水生态系统》2020,30(8):1521-1539
- Assessing biodiversity and understanding how it works is a prerequisite for species conservation. The Amazon basin is one of the main biodiversity hotspots where fish are heavily exploited for ornamental purposes.
- The ornamental trade heavily exploits the genus Apistogramma, which is one of the most species‐rich among Neotropical cichlids with 94 formally described species. This number is certainly underestimated owing to the limitations of conventional taxonomy, which is still too often based solely on morphological criteria and sometimes on few individuals.
- Most species of this genus have a high degree of endemism and are highly prized on the ornamental market, which could put them at risk. A few species are supposed to have extensive distributions, and in particular Apistogramma agassizii, present from the Amazon estuary up to the Ucayali and Marañon rivers in Peru.
- This study assessed the taxonomic status of 1,151 specimens of A. agassizii collected from 35 sites around Iquitos in the Peruvian Amazon. On the basis of molecular analyses (nuclear and mitochondrial DNA) and mate choice experiments, at least three biological species within the nominal A. agassizii were evidenced in the sampling area, which is extremely small compared with the known distribution of the species as initially described.
- According to the molecular calibrations, these three species would have diverged during the Plio‐Pleistocene. Two of them seem to be endemic from small sub‐basins, one from the Nanay River and the other from the Apayacu/Ampiyacu systems. A possible scenario that may explain the evolutionary history of these species is proposed.
- The conservation implications of these results on the estimation of the diversity of A. agassizii, of Apistogramma species in general, and of other Amazonian cichlids are discussed.
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Kevin L. Rhodes Ivy E. Baremore Brett M. Taylor Javier Cuetos-Bueno Dalia Hernandez 《水产资源保护:海洋与淡水生态系统》2021,31(3):605-619
- Camouflage grouper, Epinephelus polyphekadion (Bleeker, 1849), and squaretail coralgrouper, Plectropomus areolatus (Rüppell, 1830), are commercially important medium-bodied groupers that aggregate at specific sites and times to spawn and are highly vulnerable to fishing during these events. Populations of both species are in decline globally, such that management specifically targeting these species is warranted.
- A 12-month fish market survey in Chuuk, Federated States of Micronesia, provided an opportunity to examine age-based reproductive life history of these two groupers and assess whether current management acts to conserve them. Life history characteristics of both E. polyphekadion and P. areolatus include a functionally gonochoristic sexual pattern and rapid growth particularly during early life history.
- P. areolatus demonstrated early maturity (2.8 years) and a relatively brief lifespan (10 years), while delayed maturity (4.5 years) and higher longevity (25 years) was shown for E. polyphekadion. The spawning seasons for E. polyphekadion and P. areolatus were 2 and 3 months, respectively, which fall entirely within the January–April grouper sales, catch, and export ban period for Chuuk. Marketed catch included 22% E. polyphekadion and 15% P. areolatus juveniles, suggesting that size limits may aid in the conservation of these species.
- Findings from this and recent grouper life history studies suggest that the current 4-month ban in Chuuk be applied only to grouper species known to reproduce during these months to minimize economic impacts to fishers and market owners, and prevent shifts in fishing pressure to more vulnerable species, such as those with low population turnover times, slow growth, or late maturity. Size limits for catch, sale and export are also warranted as an additional management option.
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Riccardo Melis Laura Vacca Andrea Bellodi Alessandro Cau Cristina Porcu Maria Cristina Follesa Rita Cannas 《水产资源保护:海洋与淡水生态系统》2020,30(1):86-103
- Genetic information is crucial for the conservation of Dipturus oxyrinchus (Linnaeus, 1758), a threatened large skate with declining populations over most of its geographical range. The main aim of the present study was to investigate the genetic structure, connectivity and demographic history of the longnosed skate in Sardinia (western Mediterranean Sea).
- Patterns of population structure were assessed in 175 specimens from six sampling sites. Variation in two mitochondrial genes (cytochrome c oxidase subunit I (COI) and control region) highlighted high genetic diversity and low but significant genetic differentiation among sites, which clustered into three groups corresponding to the north‐west, north‐east and south Sardinian coasts.
- The observed genetic structuring could presumably depend on a combination of past geological events, contemporary restrictions to dispersal and biological characteristics of the species (e.g. site‐fidelity, no pelagic larval stage, limited dispersal of juveniles and/or adults).
- Demographic analyses showed signs of past population expansion, but substantial current stability of Sardinian populations. From a conservation perspective, these results are encouraging, and indicate that Sardinian populations are still large and stable, and seem not to have suffered negative side‐effects from the ever‐growing fishing pressure in the region.
- The occurrence of genetic structuring strongly supported the close monitoring of populations to identify any erosion of their gene pool, and high genetic variability of the Sardinian D. oxyrinchus populations could thus represent priority populations for conservation purposes, providing potential sources for recolonization in cases of local extinctions in other areas of the distribution range of the species.
- When the sequences from Sardinia were compared with those available from other areas, the data seem to exclude the possibility that the Atlantic and Mediterranean host totally isolated populations or even different species, as recently suggested. However, additional markers and a larger sampling sites are needed to confirm these findings.
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K. David Hyrenbach Zora McGinnis Kathleen Page Dan Rapp F. David Horgen Jennifer M. Lynch 《水产资源保护:海洋与淡水生态系统》2021,31(2):408-419
- Although the frequency of occurrence of plastic ingestion in the large-sized dolphinfish and tunas taken by the Hawai'i longline fishery is very low (frequency of occurrence < 5% of sampled individuals), the ingestion of plastic in smaller-sized specimens caught with pole-and-line gear by commercial and recreational fishers has not been investigated.
- This study examined ingestion of >0.25 mm marine plastic debris (MPD) by four predatory fish species caught by commercial fishers around the Main Hawaiian Islands, and documented ingestion in three species: 85.7% of albacore tuna (n = 7), 40.0% of skipjack tuna (n = 10) and 12.5% of dolphinfish (n = 8).
- Yellowfin tuna (n = 10) did not contain any MPD, probably owing to the high proportion of empty stomachs (60%).
- For skipjack tuna, the frequency of occurrence of MPD ingestion was significantly higher for the smaller-sized specimens caught with pole-and-line (40%), compared with the larger-sized specimens caught with longlines (0%).
- For dolphinfish, the frequency of occurrence of MPD ingestion was similar for the similar-sized specimens caught with pole-and-line and with longlines.
- The ingested MPD items were micro–meso plastics, between 1 and 25 mm. While most ingested items were fragments, albacore also ingested line and skipjack also ingested sheets.
- The predatory fishes ingested light MPD items that float in sea water, but there were species-specific differences in their polymer composition: albacore contained more polypropylene and polyethylene, and skipjack contained more elastomers, characterized by a high percentage of ester plasticizers.
- Altogether, these results suggest that albacore and skipjack tunas ingest plastic of different types and polymers. Yet more research is needed to understand how differences in vertical distribution, foraging ecology and diet influence the MPD sampled by these predatory fish species.
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Marzia Bo Martina Coppari Federico Betti Francesco Enrichetti Marco Bertolino Francesco Massa Simone Bava Guido Gay Riccardo Cattaneo-Vietti Giorgio Bavestrello 《水产资源保护:海洋与淡水生态系统》2021,31(3):543-566
- Seamounts host some of the most important deep-sea ecosystems. The unique environmental characteristics of seamounts sustain rich biological hot spots, which, in recent times, have suffered the effects of intense fishing pressure.
- Biodiversity and vulnerability data are extremely scarce for Mediterranean seamounts, and this, in addition to the complex socio-economic and juridical status of offshore sites, results in difficulty in identifying the best management strategies.
- An extensive remotely operated vehicle (ROV) survey was used to characterize the megabenthic assemblages of the summits of two upper bathyal seamounts, Ulisse and Penelope (Ligurian Sea, north-west Mediterranean Sea). The biogeographic implications of these findings and the possible environmental factors favouring the occurrence of these communities are discussed.
- High densities of abandoned, lost, or otherwise discarded fishing gear (mainly longlines) and a reduction in the average size of the fragile and slow-growing habitat-forming gorgonian Callogorgia verticillata indicate the occurrence of high levels of anthropogenic impacts on the summit regions, which are fishing grounds for artisanal and recreational fishers.
- The recovery of fishing data describing the first catches in the 1970s proved to be useful in inferring the short- and long-term effects of fishing practices in these previously unexploited offshore areas. In particular, the local extinction of demersal top predators, subjected to exceptional catches nearly 50 years ago, highlights the slow recovery rate of such species.
- Criteria defining vulnerability are discussed for the two study areas, and specific conservation actions, including the creation of regulated protected areas, are proposed.
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- Fisheries monitoring is essential to evaluate and manage fish populations. Effective monitoring is particularly challenging in low- and middle-income countries where fisheries often occur at large spatial scales and include multiple techniques. Recreational spearfishing, for instance, can be detrimental to fish populations and is often underrepresented in management strategies due to the lack of data.
- Because recreational fishers frequently share pictures of their catches online, social media can harbour valuable information. As a case study, freely available pictures in social media were used to assess the impacts of spearfishing on the endemic and endangered Brazilian parrotfish, Scarus trispinosus, that has experienced a sharp population decline in recent decades due to overfishing.
- It was found that S. trispinosus is widely captured by recreational spearfishing and at larger sizes when compared to artisanal fisheries, revealing complementary fishing pressures operating on different life stages of this species and a lack of compliance to current regulations. The number of users sharing these contents increased between 2007 and 2018, but declined thereafter until 2020.
- Identifying where spearfishing is more intense and the most targeted life-stages can inform prioritization of management strategies. Social media can be a rapid and low-cost tool to obtain nationwide fisheries information, especially for recreational fishing activities that have a flawed monitoring.
- The public disclosure of ‘trophy fishes’ can reveal lack of compliance to existing regulations and help fill critical information gaps on complementary fishing pressures. This approach may be applicable for many species and types of trophy fishing, providing valuable and useful information for management and conservation.
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Olivier Le Duc Thong Pham Van Benjamin Leprince Cedric Bordes Anh Nguyen Tuan John Sebit Benansio Nic Pacini Vinh Quang Luu Luca Luiselli 《水产资源保护:海洋与淡水生态系统》2020,30(6):1074-1087
- Next to cetaceans and megafishes, freshwater turtles are the most iconic endangered freshwater species.
- A detailed questionnaire survey conducted with more than 100 individuals from fishing communities in northern Vietnam was used to investigate the current status of Southeast Asian turtles and provides new hope concerning the survival of Rafetus swinhoei, for which recent official records in the wild are limited to a single individual in Vietnam.
- The survey included the entire Vietnamese portion of the Da River in Hoa Binh and Son La provinces, as well as the Chu and Ma river system in Thanh Hoa Province, as they are the last sites where the world's rarest and largest Asian softshell turtle has been seen. The questionnaire, conducted in Vietnamese, focused on demographic details, fishing intensity and gear, the status of fishing grounds, and the frequency of interaction with turtles.
- The great majority of fishers could recognize different turtle species from photographs and describe their preferential breeding habitats; not all knew that they are protected. A few confirmed that more than once each year they still encounter freshwater turtles during their fishing activities.
- This survey provides detailed information on sites where freshwater turtles are still seen in northern Vietnam and broadens our hope that wild individuals of the extremely rare R. swinhoei may still be present in the remaining riparian wetlands of these biodiverse, dammed, and controlled river basins in North Vietnam.