“Pig in a poke (gato por liebre)”: The “mota” (Calophysus macropterus) Fishery,Molecular Evidence of Commercialization in Colombia and Toxicological Analyses

Overfishing has affected the population abundance trends of many commercial fish species. In the Amazon, the fishery of a catfish commonly known as “mota” or “piracatinga” (Calophysus macropterus) has become an important economic activity in the region as this species has replaced a number of other overexploited great catfish species in the markets. Due to this high exploitation, ways in which to increase captures have been identified. One strategy is to use decomposing animal carcasses as bait. Such strategy has increased the hunting pressure on endangered species such as caimans and river dolphins. We investigated which catfish species are currently commercialized in Colombian fish markets using DNA barcoding, and measured mercury concentration in the tissues of fish molecularly identified as C. macropterus. We collected 86 fish samples in markets of four Colombian cities. Sixty-eight of these were identified molecularly as C.macropterus. The mercury concentration of 29 such samples was analyzed. Samples presented total Hg concentrations higher than the limit for human consumption established by the WHO (0.5 μg/g). These results are worrisome and suggest that (1) C. macropterus is a widely used fish species for human consumption in Colombia and (2) C. macropterus has high concentrations of total Hg, making its consumption a public health risk. Results presented here suggest that C. macropterus has replaced capaz in most Colombian markets. This fishery threatens wild species of river dolphins and caimans, and is also a public health risk given the high mercury levels we found in a subsample of these fishes.     

Fishery resource use in a subarctic Indian community

Cree Indians of Fort George, James Bay, northern Canada, maintain a large and successful subsistence fishery. Methods used in the fishery, seasons and locations of catch, and yield levels were studied, together with the population biology of two sea-run Coregonus species, cisco and whitefish, that dominate the catch. The fishery was characterized by a high degree of order, social regulation of the fishing effort and the gillnet mesh size, and practices that were identified as adaptations to the subarctic ecosystem. Fishing methods used permit the Cree to control the magnitude of the harvest and the species and size composition of the catch. There is evidence that fishers can alter the scarcity-abundance patterns of the fish stocks, and have a biologically measurable effect on the populations.     

Gear type,species composition and economic value of fisheries in the mangroves of Pak Phanang,Thailand

Fishing gear and methods, catch composition, annual catch numbers and the monetary value of fisheries based in the mangroves of Pak Phanang, Nakhon Si Thamarat province, Thailand, were studied from September 2004 to February 2005. The fishing gear and methods were surveyed by visual observation and interviews. Sample catches were taken for each type of fishing gear and method. Semi-closed questionnaire surveys were conducted among fishers, local traders, local administrative officers and related organizations to derive information on utilized species, gear and methods, fisher and fishery status, and trading and catch price. The Pak Phanang mangrove fishery has three types of multi-species capture gear: channel traps, gill nets and lift nets. It also has three kinds of single-species (group) gear/methods: crab traps, catfish hooks and hand capture using a long tail fishing boat. A total of 57 fish species in 27 families, and 23 shell fish species in 8 families were recorded from the catch samples. Penaeid shrimp (25%), and ambassid (31%) and mugilid (24%) fishes were the abundant groups in the channel traps, while ariid (36%) and mugilid (19%) fishes were abundant in the lift net catches. Ambassid (42%) fish dominated the gill net catches. Species richness (number of species) varied depending on sampling month and type of fishing gear. The total annual catch and its monetary value were estimated to be 442–551 tons and US $368,038–733,973, respectively. The estimated annual catch per unit area of mangrove was 63–79 kg ha⁻¹, which generated a market value of US $368,038–733,973, respectively. The estimated annual catch per unit area of mangrove was 63–79 kg ha⁻¹, which generated a market value of US 52–105.     

Bycatch of the endangered pallid sturgeon (Scaphirhynchus albus) in a commercial fishery for shovelnose sturgeon (Scaphirhynchus platorynchus)

We quantified the bycatch of pallid sturgeon Scaphirhynchus albus in Tennessee's shovelnose sturgeon ( Scaphirhynchus platorynchus) fishery by accompanying commercial fishers and monitoring their catch on five dates in spring 2007. Fishers were free to keep or discard any sturgeon they collected in their gillnets and trotlines and we were afforded the opportunity to collect meristic and morphometric data and tissue samples from discarded and harvested specimens. Fishers removed 327 live sturgeon from their gear in our presence, of which 93 were harvested; we also obtained the carcasses of 20 sturgeon that a fisher harvested out of our sight while we were on the water with another fisher. Two of the 113 harvested sturgeon were confirmed pallid sturgeon based on microsatellite DNA analyses. Additionally, fishers gave us five, live pallid sturgeon that they had removed from their gear. If the incidental harvest rate of pallid sturgeon (1.8% of all sturgeon harvested) was similar in the previous two commercial seasons, at least 169 adult pallid sturgeon were harvested by commercial fishers in the Tennessee waters of the Mississippi River in 2005–2007. If fishers altered their behavior because of our presence (i.e. if they were more conservative in what they harvested), the pallid sturgeon take was probably higher when they fished unaccompanied by observers. While retrieving a gill net set the previous day, a fisher we were accompanying retrieved a gillnet lost 2 days earlier; this ghost net caught 53 sturgeon whereby one fish was harvested but most fish were dead, including one confirmed pallid sturgeon.     

Environmental variability and the fishery dynamics of the Okavango delta, Botswana: the case of subsistence fishing

The hydrological regime of the Okavango River Basin is the main driver of ecological change in the delta. The delta supports a small-scale fishery which is a source of livelihood for communities within its fringes. The fish resource is particularly important to subsistence fishers, who have limited access to socio-economic opportunities. However, fish availability is subject to 'concentration and dilution' effects because of the hydrological regime. As a copying strategy, fishers use a variety of fishing methods to effectively harvest the delta's fish community across all its trophic levels. This exploitation regime helps to maintain the delta's species diversity and only reduces fish biomass proportionally across the different trophical levels. Furthermore, fishers have developed different fish-processing techniques to preserve their harvest for low fishing season periods to cope with low food availability. The aim of this paper therefore, was to explore spatio-temporal variations in fish availability and to show how the delta's subsistence fishers cope with this dynamicity.     

Composition of the Aboriginal harvest of fisheries resources in coastal New South Wales,Australia

A key aspect of equitable management of the world’s fishery resources is the provision of traditional fishing access for Indigenous peoples. In Australia, increased recognition of the importance of fisheries to Indigenous culture and livelihoods over recent years has created a need for information on the species targeted to support policy and management. In the State of New South Wales (NSW), research on Indigenous fisheries catch composition is limited to two major studies. Here, we compare and combine data on Indigenous catch composition from these two studies to produce a comprehensive synthesis of current knowledge of Indigenous fisheries in NSW. The species harvested include more than 150 species of finfish and invertebrates, over 90 % of which are also harvested by commercial and recreational fishers. Our findings provide an empirical basis for future development of policy and management initiatives to meet the needs of Indigenous fishers and other stakeholders, as well as the principles of sustainable fisheries harvest.     

Genetic isolation between coastal and fishery‐impacted,offshore bottlenose dolphin (Tursiops spp.) populations

The identification of species and population boundaries is important in both evolutionary and conservation biology. In recent years, new population genetic and computational methods for estimating population parameters and testing hypotheses in a quantitative manner have emerged. Using a Bayesian framework and a quantitative model‐testing approach, we evaluated the species status and genetic connectedness of bottlenose dolphin (Tursiops spp.) populations off remote northwestern Australia, with a focus on pelagic ‘offshore’ dolphins subject to incidental capture in a trawl fishery. We analysed 71 dolphin samples from three sites beyond the 50 m depth contour (the inshore boundary of the fishery) and up to 170 km offshore, including incidentally caught and free‐ranging individuals associating with trawl vessels, and 273 dolphins sampled at 12 coastal sites inshore of the 50 m depth contour and within 10 km of the coast. Results from 19 nuclear microsatellite markers showed significant population structure between dolphins from within the fishery and coastal sites, but also among dolphins from coastal sites, identifying three coastal populations. Moreover, we found no current or historic gene flow into the offshore population in the region of the fishery, indicating a complete lack of recruitment from coastal sites. Mitochondrial DNA corroborated our findings of genetic isolation between dolphins from the offshore population and coastal sites. Most offshore individuals formed a monophyletic clade with common bottlenose dolphins (T. truncatus), while all 273 individuals sampled coastally formed a well‐supported clade of Indo‐Pacific bottlenose dolphins (T. aduncus). By including a quantitative modelling approach, our study explicitly took evolutionary processes into account for informing the conservation and management of protected species. As such, it may serve as a template for other, similarly inaccessible study populations.     

Estimating historical commercial rock lobster (Jasus edwardsii) catch inside Australian State territorial waters for marine protected area assessment: the binomial likelihood method

The rock lobster (Jasus edwardsii) fishery of South Australia is the State’s most valuable fisheries resource with an export value exceeding ~AU$100 million. The fishery operates primarily inshore (<60 m), and overlaps with a series of marine protected areas (MPAs) currently proposed for State territorial waters. As a result, the need to quantify the impact of proposed MPAs on commercial landings of rock lobster within territorial waters is an integral part of the MPA assessment process. Removing fishing effort displaced by MPAs prevents a corresponding increase in exploitation outside protected zones. We describe a binomial likelihood method that utilises historical commercial catch data to estimate catch totals of rock lobster inside South Australian State waters. Lobster catches per km² showed a high level of spatial variation with estimated historical lobster catch in State waters spanning approximately three orders of magnitude. The method identified key areas where high lobster catch (up to 500 kg/km²) overlapped with State waters. Binomial likelihood outputs have particular application to the estimation of net catch loss in situations where fishery buy-back or financial compensation are a considered option as part of the MPA implementation process.     

Initial study on catch,species composition and reproductive biology of fishes off the south‐west coast of Sri Lanka,targeted by ring nets while utilizing natural floating objects

This study evaluates the catch rates, species composition and reproductive biology of flotsam‐associated fishes targeted by ring nets off the southwest coast of Sri Lanka. Catch and number of multiday boats operating with ring nets were collected at Beruwala fishery harbor on the southwest coast of Sri Lanka, March to October 2013, by making fortnightly field visits. Fish samples were collected randomly from the unloaded ring net catches to analyze reproductive biology. Twelve fish species belonging to four major families: Scombridae, Carangidae, Coryphaenidae and Balistidae were identified in the ring net catches and five species, Decapterus russelli, Katsuwonus pelamis, Thunnus albacares, Elagatis bipinnulata and Canthidermis maculatus were predominant. An average of 25 ± 12% multiday boats landing at the Beruwala fishery harbor operated with ring nets each month, with an average monthly catch rate fluctuating from 730 ± 101 to 3924 ± 1094 kg per boat per trip. Catch rates of tunas and carangids were significantly higher than the other fish groups (anova ; d.f. = 3, P < 0.05). Total fish landed by ring nets at the Beruwala fishery harbor during the study period was 1456 tonnes. Species belonging to the family carangidae had the highest percentage contribution (46.6%) to the ring net landings followed by tuna (34%). Similar‐size individuals ranging from 24 to 31 cm were landed by ring nets, with all landed individuals belonging to K. pelamis, T. albacares and E. bipinnulata having immature gonads. The findings of this study will be useful locally as well as regionally to manage the ring net fishery and to aid in implementing measures to manage the highly migratory tuna species.     

Commercial coral-reef fisheries across Micronesia: A need for improving management

A dearth of scientific data surrounding Micronesia’s coral-reef fisheries has limited their formal assessment and continues to hinder local and regional management efforts. We approach this problem by comparing catch-based datasets from market landings across Micronesia to evaluate fishery status in the Commonwealth of the Northern Mariana Islands (CNMI), Guam, Yap, and Pohnpei. Initial examinations found that calm weather and low lunar illumination predicted between 6% (Yap) and 30% (CNMI) of the variances in daily commercial landings. Both environmentally driven catch success and daily catch variability increased in accordance with reef-fish demand indices. Subsequent insight from species composition and size-at-capture data supported these findings, highlighting reduced trophic levels and capture sizes where higher human-population-per-reef-area existed. Among the 12–15 target species and/or species complexes that accounted for 70% of the harvest biomass, capture sizes were consistently smallest for CNMI and Guam, often below the reported mean reproductive sizes. Comparatively, Pohnpei has the greatest potential for reef fisheries, with a large reef area (303 km²) and a moderate human population (34,000 people). However, the estimated harvest volume of 476 mt year⁻¹ was 8–9 times higher than other jurisdictions. Even on Yap where the reef-fish demand index was lowest (67.7 people km⁻² reef habitat), many target fish were harvested below their mean reproductive sizes, including the iconic green bumphead parrotfish and humphead wrasse, as well as several other herbivores. We discuss our results with respect to the contemporary doctrine surrounding size-spectra, catch composition, and catch frequencies that afford insight into fishery pressure and status. We posit that regional catch-based policies (initially) instituted at the market level, combined with area and gear-based restrictions, represent plausible vectors for improving Micronesian fisheries.     

A quantitative comparison of recreational spearfishing and linefishing on the Great Barrier Reef: implications for management of multi-sector coral reef fisheries

This study compared the catch composition, catch per unit effort, and incidental impacts of spearfishers and linefishers engaged in a structured fishing program whereby fishing effort was standardized across time, space and skill level. It was found that (1) the catch composition of both groups of fishers overlapped considerably, (2) the numbers of target fish caught by spearfishers (156) and linefishers (168) were not significantly different, (3) the mean size of target fish caught by spearfishers (1.95 ± 0.1 kg, ±SE) was significantly larger than the mean size of target fish caught by linefishers (1.27 ± 0.06 kg), and (4) spearfishers retained 43% more biomass of target species than did linefishers (304 versus 213 kg, respectively). However, linefishers used ∼1 kg of bait for every 3 kg of target fish that were captured. Linefishers also caught far more undersized, undesirable, or protected fishes (i.e., bycatch) and caused far more pollution (i.e., lost gear) than did spearfishers. It is concluded that the overall impacts of recreational spearfishing and linefishing on fishery resources of the Great Barrier Reef are broadly equivalent (per unit of fishing effort), and that management regulations should be applied equitably across both fishing sectors. A management strategy of this type will simplify enforcement of fisheries regulations and avoid discrimination of particular fishers in local communities where both fishing methods are socially or culturally important.     

Discards in bottom‐trawl fishery in the western Black Sea (Turkey)

The aim of this study was to estimate the discards of target and non‐target species from bottom trawlers (rhombic and 40 mm cod end mesh size nets) in the Black Sea. On‐board sampling was conducted on the southwestern coasts of the Black Sea in the fishing ports of Rumelifeneri and Igneada for a total of 66 hauls on two commercial bottom trawlers from October 2012 to April 2013 and from October 2013 to April 2014. A total of 32 species were captured, including 25 species of fish, three crustacea, two echinodermata and two mollusca. Mullus barbatus and Merlangius merlangus euxinus were the target species, whereas 24 species were always discarded. Scophthalmus maximus and Pomatomus saltatrix were always retained. The two regions were similar in terms of catch and discard compositions, CPUE, DPUE and discard ratio. Discarding is important in the Black Sea commercial bottom trawl fishery and accounts for as much as 31.4% of the total bottom trawl catch. The results showed that the discard rates varied among species, depths (p = .04) and seasons (p = .0001). Finally, it was concluded that in the western Black Sea, when the impacts of depth and season are considered, that the discard quantity can be reduced.     

Landed and discarded catches from commercial prawn trammel net fishery

This study presents estimates of numbers and biomass of discarded and landed catches from the commercial prawn trammel net fishery in İzmir Bay. A total of 43 finfish and 29 invertebrate species were identified in catches sampled between May and October 2003, with 26 species landed by fishers and 46 species discarded. Melicertus kerathurus, Mullus barbatus and Solea solea dominated the landed catches. Average ratio of landed to discarded fish by number and weight was estimated as 1 : 2.32 and 1 : 0.77, respectively, demonstrating relatively low by‐catch ratios compared to other shrimp by‐catch studies. This study shows that trammel nets have a much lower discard ratio than the shrimp trawls in other parts of the world. The benefits of shifting toward passive trammel nets in coastal areas are discussed.     

Quantification of the Early Small-Scale Fishery in the North-Eastern Baltic Sea in the Late 17th Century

Historical perspectives on fisheries and related human behaviour provide valuable information on fishery resources and their exploitation, helping to more appropriately set management targets and determine relevant reference levels. In this study we analyse historical fisheries and fish trade at the north-eastern Baltic Sea coast in the late 17th century. Local consumption and export together amounted to the annual removal of about 200 tonnes of fish from the nearby sea and freshwater bodies. The fishery was very diverse and exploited altogether one cyclostome and 17 fish species with over 90% of the catch being consumed locally. The exported fish consisted almost entirely of high-valued species with Stockholm (Sweden) being the most important export destination. Due to rich political history and natural features of the region, we suggest that the documented evidence of this small-scale fishery should be considered as the first quantitative summary of exploitation of aquatic living resources in the region and can provide a background for future analyses.     

Fish by-catch species from coastal small-scale shrimp trammel net fishery in the Aegean Sea (Izmir Bay, Turkey)

Fish by‐catch from coastal small‐scale shrimp trammel net fishery was estimated from fishery‐dependent surveys in Izmir Bay (Aegean Sea), Turkey, during the 2004 and 2005 fishing seasons. Sampling data were obtained from 170 observations onboard 18 commercial fishing vessels. Fifty‐two species belonging to 31 families of fish, including cephalopods, constituted the by‐catch. Diplodus annularis was the most abundant by‐catch species followed by Loligo vulgaris > Sepia officinalis > Mullus barbatus > Boops boops > and Solea vulgaris. The estimated total ratio of fish by‐catch to shrimp was 1 : 1.09 kg.     

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.     

Present status of fisheries in Turkey

Turkey’s natural and ecological situations are very suitable for aquaculture. Turkey also has a wide variety of freshwater and marine species comprising trout, carp, sea bass, sea bream, turbot, mussel, crayfish, etc. The total production of fish and shellfish was 646,310 tons in 2008. The contribution of freshwater catch to total fishery production is relatively small. Capture fisheries production amounted to 494,124 tons whilst aquaculture production was 152,186 tons in the same year. In Turkey, Engraulis encrasicholus (anchovy) is the main caught sea fish species. Fisheries in the Black Sea are the most important fishery by far and show the greatest variations in total catch. Alburnus tarichii (a local species belonging to Cyprinidae) and Cyprinus carpio (the common carp) are the most important species caught from freshwaters. Aquaculture is going to play an increasingly important role in the Turkish economy, as fishery products are the only products of animal origin that can be exported to the EU. There has been a fast increase in the aquaculture production in Turkey with the implementation of scientific and technological modernization. For example, total aquaculture production for 1986 and 2008 was 3,075 and 152,186 tons, respectively. The percentage of aquaculture in total fish production has been rising every year. The ratio of cultured fish production to total fish production was 1.5% in 1990 s, 13.57% in 2000 and more than 20% in 2005. It was 23.55% in 2008. Trouts are the main cultured freshwater fish species. Raceways and floating cages are employed in culture of trout. Carps are also important cultured freshwater fish species. Sea bass and gilthead sea bream are grown marine fish species. Floating cages, off-shore and earthen ponds are used for marine fish species culture. There has been an increase in fishery exports and imports in recent years. It was more than US500 million in 2008, but that of 2004 was just over US 500 million in 2008, but that of 2004 was just over US 233 million. However, aquaculture production is still far away from the production targets and fisheries sector is not an important part of the economy at present.     

Fish Rejections in the Marine Aquarium Trade: An Initial Case Study Raises Concern for Village-Based Fisheries

A major difficulty in managing wildlife trade is the reliance on trade data (rather than capture data) to monitor exploitation of wild populations. Collected organisms that die or are rejected before a point of sale often go unreported. For the global marine aquarium trade, identifying the loss of collected fish from rejection, prior to export, is a first step in assessing true collection levels. This study takes a detailed look at fish rejections by buyers before export using the Papua New Guinea marine aquarium fishery as a case study. Utilizing collection invoices detailing the species and quantity of fish (Actinopteri and Elasmobranchii) accepted or rejected by the exporting company it was determined that, over a six month period, 24.2% of the total fish catch reported (n = 13,886) was rejected. Of the ten most collected fish families, rejection frequency was highest for the Apogonidae (54.2%), Chaetodontidae (26.3%), and Acanthuridae (18.2%) and lowest for Labridae (6.6%) and Hemiscylliidae (0.7%). The most frequently cited reasons for rejection were fin damage (45.6% of cases), undersized fish (21.8%), and fish deemed too thin (11.1%). Despite fishers receiving feedback on invoices explaining rejections, there was no improvement in rejection frequencies over time (r = -0.33, P = 0.15) with weekly rejection frequencies being highly inconsistent (range: 2.8% to 79.4%; s = 16.3%). These findings suggest that export/import statistics can greatly underestimate collection for the marine aquarium trade as additional factors such as fisher discards, escapees, post-collection mortalities, and unregulated domestic trade would further contribute to this disparity.     

Assessing the potential biological implications of recreational inshore fisheries on sub‐tidal fish communities of Azores (north‐east Atlantic Ocean) using catch and effort data

Recreational inshore fishing activities practiced on Faial and Pico Islands (Azorean archipelago) were surveyed between October 2004 and September 2005. Recreational inshore fishers employ three main methods of fishing (shore angling, spear fishing and intertidal collecting). The method that demanded the highest fishing effort (number of fishing operations) was shore angling, followed by intertidal collecting and spear fishing. Shore angling produced the highest diversity of catch composition (38), which is in part explained by the seven fishing techniques used by shore anglers. The estimates of annual catch were higher for shore angling than spear fishing (51·2 and 6·3 t) even though they were lower than commercial artisanal fishing (442 t). The weighted mean trophic level and vulnerability index values in the fish catch were higher for spear fishing (3·4 and 50·9) than for shore angling (3·1 and 44·5). Cumulative pressure by different recreational fishing activities was detected on species already subject to a heavy pressure from Azorean commercial fishing, and on vulnerable and top‐predator species. There are important biological and ecological implications whereby fishery managers should implement additional regulations such as prohibiting catches of the most vulnerable species.