Line Fishery Research Articles

Using dolphins to catch tuna: Assessment of associations between pantropical spotted dolphins and yellowfin tuna hook and line fisheries in Hawai‘i

In Hawaiian waters fishermen use the association between pantropical spotted dolphins (Stenella attenuata) and yellowfin tuna (Thunnus albacares) to catch tuna. Targeting fishing effort around or in spotted dolphin groups has the potential to lead to bycatch, and anecdotal reports of hooking dolphins exist. We recorded information on fishing vessels associated with spotted dolphin groups from 2008 through 2018 to inform discussions about potential bycatch. Associations occurred from Oʻahu to Hawaiʻi Island, but were most prevalent off Hawaiʻi Island, where 29.7 % of spotted dolphin groups had fishing vessels present. When fishing vessels were present, trolling through the dolphin group envelope was recorded in 91.7 % of encounters, and re-positioning through the dolphin group and dropping hook and line fishing gear at the leading edge of the group was recorded in 54.2 % of encounters (most of which also had vessels trolling through). Associations occurred over all four oceanographic seasons, with no obvious seasonal trend. Off Hawaiʻi Island, fishing vessels with spotted dolphin groups were concentrated in a narrower depth range than dolphin groups without fishing vessels present. Groups with fishing vessels were also concentrated in a smaller geographic area that corresponded to proximity to harbors and boat launches. The number of fishing vessels that associated with spotted dolphin groups off Hawaiʻi Island was estimated in the low hundreds (159, (SD = 12) for 2012; 330 (SD = 17) for 2013). Overall, our results suggest that fishing vessel associations with pantropical spotted dolphins in Hawaiian waters are widespread, occur frequently, and involve many participants, suggesting the risk of accidental hooking may be greater than perceived.

Operational interactions between sea lion species (Otariinae) and commercial fisheries

Many marine mammal species, such as pinnipeds, have shown an increased frequency of interaction with fisheries. Thus, we aimed to investigate the operational interactions between commercial fishing and sea lion species of all five continents, between 1982 and 2018. We found 130 publications in which operational interactions between commercial fisheries and the species of sea lions were detected, in 12 countries. These interactions included bycatch, presence of the animals around boats, depredation, gear damage, entanglement in lost/discarded fishing gear, boat collisions, aggressions, gear-related injuries and harassment. Trawl and gillnet fisheries showed significantly increased association with bycatch, although purse seine fishing was reported as having the largest groups of pinnipeds in the interactions. Gillnet and line fisheries registered more events of depredation and gear damage. Other interactions, such as entanglement and aggressions, were also very common for all species. We suggest that the interactions should be monitored using the data of onboard observers from different fleets and fisheries. Bycatch limits, change in fishing practices, decreased fishing effort, and the establishment of effective MPAs may reduce impact on the fauna. Moreover, data on bycatch should be standardized to enable comparisons between fisheries and locations. The extent of commercial losses caused by pinnipeds should also be characterized to depict the real impact of operational interactions in fisheries economy. Lastly, the identification of interaction hotspots can enable efficient conflict management in the affected areas.

Operationalizing triple bottom line harvest strategies

Abstract Over the past 50 years, the diversity of fisheries types being actively managed has changed from mainly data-rich, industrial sectors to more socially, economically, and environmentally complex multispecies and multisector fisheries. Accompanying this change has been a broadening of management objectives to include social and economic considerations with traditional resource sustainability objectives, the so-called triple bottom line, and the need to include these considerations into harvest strategies. The case of a line fishery in Australia’s Great Barrier Reef is used as a demonstration of the first steps in implementing triple bottom line harvest strategies. This fishery has several disparate sectors including commercial, tourism, and recreation; targets multiple but important reef species; and is undertaken in a World Heritage Site. This work highlights the need for a much-expanded set of objectives elicited from stakeholders that are either included in the trade-off analyses of the different harvest strategies or directly in an optimization. Both options demonstrated that a paradigm shift is required to emphasize representative participatory management systems that assemble teams from quite different backgrounds and viewpoints; use much broader set of objectives; and modify tools and (especially) the data collected within revised monitoring programmes to underpin these tools.

Bait specificity in Hook and line fishery of River Ganga and associated conservation issues

Recent survey in lower 1,110 km stretch of River Ganga regarding ‘hook and line’ fishery revealed that fishers apply their inherited indigenous knowledge for selection of bait to harvest finfish and shellfish from river water. A total number of 26 different types of baits under 07 categories were recorded. Six varieties of fish species and four types of insects are found to be prevalent for catching carnivorous fishes. Five specially modified indigenous types of bait moulded with fish attractants were also documented. Bait-fish species association in hook and line fishery of river Ganga is discussed. Feeding habits of the target fishes was compared with the type of baits employed. Conservation issues associated with hook and line fishery is highlighted along with possible remedial measures. Different varieties of hook & line fishery which are in operation in river Ganga are briefly described. Indigenous Traditional Knowledge (ITK) associated with hook & line fishery needs to be properly documented and preserved for developing and encouraging ‘sport fishery’ in River Ganga.

Lesson learned of EAFM from pole and line fishery based in Sikka Regency, Nusa Tenggara Timur

Sikka Regency, Nusa Tenggara Timur is one of the key landing places for tuna in Indonesia’s archipelagic waters (IAW), which was selected for pilot scale application of EAFM. This study was aimed to identify some best practices of the EAFM application from pole and line fishery based in Sikka Regency. Pole and line data were collected by the observer and port sampling programs, data from handline fishery collected from other areas within the IAW was also investigated. Furthermore, for broader comparison purposes, trends from purse seine fishery operated in other areas within the IAW were also used. Data from pole and line fishery in Sikka Regency were analyzed to obtain length distribution by gear. Stakeholder consultative meetings were conducted to investigate some key issues and possible improvements for the fishery. Skipjack was the most predominant species caught by pole and line and purse seine (> 60%) but mostly immature fish. All yellowfin tuna caught by pole and line and purse seine was immature. It is recommended to reduce small-sized yellowfin catch and to maximize the economic benefit to local fishers. In addition, improvement of FAD management implementation, monitoring, and law enforcement are required reflected best practice of EAFM.

KELAYAKAN FINANSIAL USAHA PERIKANAN HUHATE DI KECAMATAN SAPARUA KABUPATEN MALUKU TENGAH

Saparua is a district in Central Maluku Regency which has 8 units of huhate (pole and line) fishing fleet and can be operated throughout the season. This condition shows that this business should be able to provide benefits, both for the owners and fishermen. However, the utilizing of skipjack resources that have exceeded the MSY value and also the substantial operational costs cause income to decline. Therefore this study aims to analyze the financial feasibility of the pole and line fisheries business in Saparua District. A survey for 5 pole and line business units in Saparua was conducted to obtain data, which were then analyzed by using several investment criteria such as NPV (Net Present Value), IRR (Internal Rate of Return), and B / C (Benefit Cost Ratio). The results show that: 1). The implementation of business management is still simple, but the tasks division among fishermen is clear. The decision is generally made by the owner. The frequency of fishing depends on the fishing season. During the west season, the fishing ground is in Banda Sea to the southern part of Seram Sea, while in the eastern season is in the northern part of Seram Sea; 2). Based on the pattern of revenue sharing, the average fishermen's income / month is lower than the minimum wage provincial (UMP) in Maluku; and 3). The highest economic benefit is achieved by the 4th pole and line unit, as well as the B / C Ratio criteria index so that it becomes a development priority because B / C Ratio shows the comparison of sacrifice (output) and results (input).

KEBIJAKAN PENGEMBANGAN PERIKANAN HUHATE DI MALUKU

Skipjack resources are quite potential in Maluku waters and are generally caught with pole and line. Skipjack is an important economic commodity with the aim of domestic and export markets, so it is expected to improve the welfare of the community. The purpose of this study is to formulate a pole and line fisheries development policy strategy in Maluku. The analytical method uses the SWOT approach technique and continued with AHP. Policy priorities for pole and line fisheries development in Maluku include: (1) optimal utilization of fishery resources; (2) empowering fishing communities; (3) government and private collaboration in the field of fisheries; (4) increasing business productivity; (5) market development through product quality improvement; (6) increasing capital assistance for business development; (7) strengthening the quality of fishermen's resources; and (8) supervision and law enforcement in the field of fisheries.

Length-weight relationships of three reef-associated fishes Lutjanus gibbus , Pinjalo lewisi and Pristipomoides filamentosus off Kochi, southwest coast of India

Length-weight relationships (LWRs) of three reef-associated fishes belonging to the family Lutjanidae viz ., Lutjanus gibbus (Forsskal, 1775), Pinjalo lewisi Randall, Allen & Anderson, 1987 and Pristipomoides filamentosus (Valenciennes, 1830), were estimated based on 548 samples collected from trawl net and hook and line fishery off Kochi, southwest coast of India. Sampling was done at Kochi (Lat. 09°56′327′′N, Long. 76°15′764′′E) and Munambam (Lat. 10°10′965′′N, Long. 76°10′258′′E) landing centers from May 2017 to November 2019. The estimated coefficient (b value) ranged from 2.597 ( P. lewisi , N = 89) to 2.902 (P. filamentosus , N = 240). Coefficient of determination (r2) ranged from 0.906 ( L. gibbus ) to 0.952 ( P. filamentosus), indicating a strong functional LWRs that were highly significant (p <0.001). The study reports the new maximum total length (TLmax) for P. lewisi and also records first estimates of length-weight relationships for three major species of snappers from the region. The generated LWR parameters will be of great importance in evaluating the biological changes in fish stocks and for developing sustainable management measures for snappers in the southeastern Arabian Sea.

Cost-effective mitigation strategies to reduce bycatch threats to cetaceans identified using return-on-investment analysis.

Globally, fisheries bycatch threatens the survival of many whale and dolphin species. Strategies for reducing bycatch can be expensive. Management is inclined to prioritize investment in actions that are inexpensive, but these may not be the most effective. We used an economic tool, return-on-investment, to identify cost-effective measures to reduce cetacean bycatch in the trawl, net, and line fisheries of Australia. We examined 3 management actions: spatial closures, acoustic deterrents, and gear modifications. We compared an approach for which the primary goal was to reduce the cost of bycatch reduction to fisheries with an approach that aims solely to protect whale and dolphin species. Based on cost-effectiveness and at a fine spatial resolution, we identified the management strategies across Australia that most effectively abated dolphin and whale bycatch. Although trawl-net modifications were the cheapest strategy overall, there were many locations where spatial closures were the most cost-effective solution, despite their high costs to fisheries, due to their effectiveness in reducing all fisheries interactions. Our method can be used to delineate strategies to reduce bycatch threats to mobile marine species across diverse fisheries at relevant spatial scales to improve conservation outcomes.

Exploitation may influence the climate resilience of fish populations through removing high performance metabolic phenotypes

Physiological rates and processes underpin the relationships between ectothermic organisms, such as fish, and their environment. The response and persistence of fish populations in an increasingly variable ocean is dependent on the distribution and diversity of physiological phenotypes. Growing evidence suggests that fisheries exploitation can selectively target certain physiological and behavioural phenotypes, which may shift exploited populations to altered physiological states. Here we test if commercial fisheries have the potential to do this in a “natural laboratory” along the South African coast. We compare metabolic traits of exploited and protected populations of the fish species, Chrysoblephus laticeps, which is a major component of the South African hook and line fishery. We find that high-performance aerobic scope phenotypes are reduced in the fished population. The most likely mechanism for this finding is a positive relationship between aerobic scope and capture vulnerability in passive-gear fisheries. Our results further highlight the selective nature of capture-fisheries and suggest that exploitation has the capacity to alter climate responses of fish populations on a physiological level. Our finding also implicates how Marine Protected Areas, through harbouring individuals with a greater diversity of physiological traits, may provide greater fish response diversity to environmental variability.

Diversity of reef associated fishes in hook and line fishery at Mandapam, Gulf of Mannar, south-east coast of India

Reef associated fishes landed by hooks and lines at Mandapam landing centre in Ramanathapuram District, Tamil Nadu for a period of four years from October 2008 to May 2012 were studied based on fortnightly samplings. The hook and line fishing is seasonal in Gulf of Mannar and lasts for six months annually from October - November to April - May, as this area remains rough during the rest of the year. The average annual landing of fish during the study period was 171 t with a peak of 295 t in 2008-09 and showed a decline since then. A total of 32 species of reef associated fishes belonging to 14 families were landed. Among them, Sphyraena barracuda contributed the maximum with a share of 42% followed by Caranx heberi (15%). Family-wise landings indicated the dominance of Sphyraenidae (46%). The diversity index (H’) was the highest during 2008-09 and the evenness of distribution of individuals among different species did not show significant variation in different years. Funnel plots of average taxonomic distinctness (∆+ ) and variation in taxonomic distinctness (λ+ ) indicated that the values in most of the years are within the normal limits.

Balık bırakma takımlarının barotravma tedavi performansı ve balıkçılık operasyonlarına etkileri

The aim of this study is to analyze the barotrauma treatment performance of different fish release devices and its effects on different fishing operations. Experiments were carried out between September 2017 and April 2018 in the Iskenderun Bay, located in the Eastern Mediterranean. Fishing Release Hook (FRH), Fish Release Clamp (FRC) and Fish Release Basket (FRB) were tested in three different fishing activities, which are longline, hand line and bottom trawl fishery, respectively for Epinephelus aeneus, Epinephelus costae and Nemipterus randalli. They were released into the sea after fishing operations. Study results showed that fish release devices were very effective for barotrauma treatment. The use of FRB is suitable for bottom trawl fishing, while the use of FRH and FRC is more ergonomic in longline and hand line fishery.

KELAYAKAN USAHA POLE AND LINE DI NEGERI HATIVE KECIL KOTA AMBON

Skipjack (Katsuwonus pelamis) is a superior commodity of Maluku which is generally caught by pole and line. This pole and line business in Maluku, especially in Ambon is currently faced some problems including the availability of live bait, distant of fishing ground that have impact on fishing trips and operational costs. Even the investment of this business is quite large, but it is managed simply. This study aims to analyze the feasibility of pole and line fisheries business in Negeri Hative Kecil, Ambon. The survey was conducted on 5 pole and line business units and the data obtained were analyzed with 4 investment criterias. The results show that 1). The average fixed costs, variable costs and revenues of the 5 pole and line business units during the year amounted to Rp 80,566,238; Rp. 72,571,200 and Rp. 878,034,000; and 2). The five pole and line business units in Negeri Hative Kecil are feasible to be developed. The highest NPV value is the second unit, Rp 298,623,599; IRR 38.33%; B/C value 3.04 with a payback period (PP) 1.17 years.

Preliminary evaluation of by-catch, mortality and yield per recruit for the Sea bass, Dicentrarchus labrax in hand line fisheries, Bardawill Lagoon, North Sinai, Egypt

Preliminary evaluation of by-catch, mortality and yield per recruit for the Sea bass, Dicentrarchus labrax in hand line fisheries, Bardawill Lagoon, North Sinai, Egypt

Length–weight relationships for estuarine fishes in South Brazil

The present study reports the length‐weight relationships (LWRs) for 18 estuarine species sampled in Guaratuba Bay, South Brazil. For the majority of these 18 species the LWRs are known from the literature, but these estimates do not consider sexes separately which is done in this contribution. Different fishing gears were used in the samplings (cylindrical nets – 1 mm mesh size, bottom trawls – 250 mm mesh size in the arms and 12 mm mesh size in the bag, beach seine – 5 mm mesh size and hook and line fishery) between September 2007 to April 2014. The specimens were sexed and the LWRs were calculated for each sex separately. There were differences between sexes in growth type, showing the importance of sexing in these studies. We reported for the first time (based on FishBase) the LWRs for two species: Ctenogobius shufeldti and Hypleurochilus fissicornis.

Improving guidelines for implementing harvest strategies in capacity-limited fisheries – Lessons from Tonga's deepwater line fishery

The majority of the world's fisheries lack formal management and assessment due to limitations in data, management capacity, or both. Capacity-limited fisheries generally contain some combination of limited infrastructure, personnel or expertise which hampers the ability of fisheries administrations to develop, implement and maintain desired management structures. Fisheries that fall within this category are at greater risk of performing poorly in terms of sustainability and economic benefits. In the process of applying a number of recently developed data-poor specific tools to Tonga's deepwater line fishery, it was apparent that reconciling the lack of resources with options for management required greater attention. Some of the challenges encountered are highlighted herein and processes to consider in order to overcome these are discussed. This resulted in a reprioritisation of the stepwise processes often used to develop harvest strategies by giving earlier prominence to management capacity and stakeholder engagement within a more iterative framework. This provides capacity-limited managers with a mechanism to develop a coherent harvest strategy across all components that is more viable long-term, irrespective of available management resources. Our case study extends the discussion on harvest strategies from data-rich to data-poor fisheries to include those fisheries that are both data-poor and capacity-limited. Application of formalised harvest strategies has been promoted as a tool to relieve the excessive fishing pressure apparent in many regions. The proposed refinements to the harvest strategy development process proposed here should improve capacity for fisheries management in circumstances where it is lacking.

Fish community and single-species indicators provide evidence of unsustainable practices in a multi-gear reef fishery

Using information on the species composition and length-frequencies of fish caught in the spear and hook and line fisheries of Glover’s Reef Marine Reserve, Belize, we evaluated changes between 2004–2010 and 2011–2017 in single-species and ecosystem sustainability indicators. The two gears differed in species caught, and both changed species composition between time periods, with the line fishers targeting smaller species, and the spear fishers responding to a parrotfish ban by catching more snappers and small groupers, as well as grey angels. Both gears caught smaller fish in 2011–2017 compared to 2004–2010, indicating overfishing. Species often caught immature were black grouper, Nassau grouper and mutton snapper with spears, and black snapper with lines. Most fish of other species were mature, but many were smaller than the optimal size for harvest. Fishing mortality rates were higher than natural mortality rates for most species in both gears in both time periods, whether calculated from average length or by length-based spawning potential ratio (LBSPR), implying that most populations were experiencing overfishing. Many species also had a low spawning potential ratio, implying a high probability that they were overfished. In general, many species were subject to unsustainable levels of fishing, and, according to the Froese indicators, some would benefit from size limits to protect immature individuals. These results are supported despite uncertainty in life history parameters for fishes in Belize, and differences between data poor assessment methods.

Who is fishing on what stock: population-of-origin of individual cod (Gadus morhua) in commercial and recreational fisheries

AbstractAtlantic cod (Gadus morhua) in Skagerrak are structured into distinct ecotypes or stock components that have been severely depleted over the past decades. To improve our understanding of how local commercial and recreational fisheries influence cod stocks, we investigated whether these user groups target different stock components of cod. Cod were sampled from the recreational rod and line fishery and from commercial shrimp trawlers catching cod as by-catch. Based on a large set of single nucleotide polymorphisms (SNPs), we defined a subset of 27 semi-diagnostic SNPs designed to discriminate between two cod stock components: “inner fjord” cod and “North Sea” cod, designated by their dominant habitat preferences. Genetic assignments of fishery-caught cod indicated that 4% of individuals caught by shrimp trawlers belonged to the inner fjord cod component and 96% to the North Sea, whereas among cod caught by recreational fishers, the estimated percentages were 11.8 and 88.2%, respectively. Our findings confirm the existence of two sympatric cod stock components in coastal Skagerrak, indicating that existing management units are biologically inappropriate and should be reconsidered. Furthermore, more attention should be given to recreational angling to reduce fishing mortality on the depleted inner fjord cod component.

Economic analysis of hook and line fishery of Thiruvananthapuram coast, Kerala

Hook and line fishing has been used for the last two decades along the Vizhinjam Coast targeting mainly tunas especially bullet tuna. The fishing methodology is in use for more than several decades, but systematic study in relation to the modifications in fishing practice and its impact on the improvement in catch and income generation of fishermen has not yet been done. This paper aims to bring out the modifications in the gear/ craft and area of operation of line fishery and its impact on the income generation of fishers in the Vizhinjam Coast.

Use of different approach in finding catch effort relationship in hook and line fishery in Kombuthurai village of Thoothukudi district of Tamil Nadu

Kombuthurai has been described as a fishing village in Thoothukudi district, Tamil Nadu which has gained immense importance by practicing sustainable fishing practices. In Kombuthurai village during 2009-2013, catch per unit effort (CPUE) has varied from 0.20 tonnes to the maximum of 0.25 tonnes during this period. It is interesting to know that despite the range of effort varying from 1598hrs to 1720hrs, the catch remained in the range of 347.4 tonnes to a maximum of 430.8tonnes. The influence of various variables (latitude, longitude, distance, depth, seasons, years and fishing gear type) on CPUE was studied by General Linear Model (GLM) and Generalized Linear Model (GLMs). Normal distribution with identity link function and a gamma distribution with log link function were used in GLMs. The variables that were found to be significant in both of the models and distributions are year and season. GLM model was good fit with R2 ranging from 67.60% to a high of 91.7%.The low and high abundance of CPUE were categorized taking the below and above average CPUE. A binary logistic regression model was used between the CPUE abundance and with above mentioned independent variables. The binary logistic regression model explained 75.4% (Nagelkerke R2) of the variance in high CPUE abundance and correctly classified 88% of cases. The independent variable such as latitude, longitude, depth, and distance added significantly to the model, but the year, season and hooks did not add significantly to the model.