Management Of Tropical Fisheries Research Articles

Exploring uncharted territory: new frontiers in environmental DNA for tropical fisheries management.

Tropical ecosystems host a significant share of global fish diversity contributing substantially to the global fisheries sector. Yet their sustainable management is challenging due to their complexity, diverse life history traits of tropical fishes, and varied fishing techniques involved. Traditional monitoring techniques are often costly, labour-intensive, and/or difficult to apply in inaccessible sites. These limitations call for the adoption of innovative, sensitive, and cost-effective monitoring solutions, especially in a scenario of climate change. Environmental DNA (eDNA) emerges as a potential game changer for biodiversity monitoring and conservation, especially in aquatic ecosystems. However, its utility in tropical settings remains underexplored, primarily due to a series of challenges, including the need for a comprehensive barcode reference library, an understanding of eDNA behaviour in tropical aquatic environments, standardized procedures, and supportive biomonitoring policies. Despite these challenges, the potential of eDNA for sensitive species detection across varied habitats is evident, and its global use is accelerating in biodiversity conservation efforts. This review takes an in-depth look at the current state and prospects of eDNA-based monitoring in tropical fisheries management research. Additionally, a SWOT analysis is used to underscore the opportunities and threats, with the aim of bridging the knowledge gaps and guiding the more extensive and effective use of eDNA-based monitoring in tropical fisheries management. Although the discussion applies worldwide, some specific experiences and insights from Indian tropical fisheries are shared to illustrate the practical application and challenges of employing eDNA in a tropical context.

Hasil Tangkapan Ikan Demersal Dengan Pancing Dasar Di Teluk Nalahia, Maluku Tengah

Small scale fisheries are commonly multi-species fisheries practice which targeting on varied species and sizes that provide better income using multi-gear. Yet, tropical fisheries management more focuses on single-species management including studies to support the management. In this study, we analyzed the catch of hand line using multi-species approachment, size abundance spectrum. Hand line with hook size 13 and 15, 64 individual were collected during 10 trips of fishing at Nalahia Bay. Represented of 34 species from 15 family, the catch of hand line has ecological function from herbivores to piscivores, 2 to 4.5 of trophic level. Abundance size spectrum of hand line showed that Nalahia Bay comprehends high diversity of demersal fish and hand lines exploit proportionally to the available productivity.

Hasil Tangkapan Ikan Demersal Dengan Pancing Dasar Di Teluk Nalahia, Maluku Tengah

Small scale fisheries are commonly multi-species fisheries practice which targeting on varied species and sizes that provide better income using multi-gear. Yet, tropical fisheries management more focuses on single-species management including studies to support the management. In this study, we analyzed the catch of hand line using multi-species approachment, size abundance spectrum. Hand line with hook size 13 and 15, 64 individual were collected during 10 trips of fishing at Nalahia Bay. Represented of 34 species from 15 family, the catch of hand line has ecological function from herbivores to piscivores, 2 to 4.5 of trophic level. Abundance size spectrum of hand line showed that Nalahia Bay comprehends high diversity of demersal fish and hand lines exploit proportionally to the available productivity.

The contribution of macroalgae‐associated fishes to small‐scale tropical reef fisheries

AbstractMacroalgae‐dominated reefs are a prominent habitat in tropical seascapes that support a diversity of fishes, including fishery target species. To what extent, then, do macroalgal habitats contribute to small‐scale tropical reef fisheries? To address this question we: (1) Quantified the macroalgae‐associated fish component in catches from 133 small‐scale fisheries, (2) Compared life‐history traits relevant to fishing (e.g. growth, longevity) in macroalgal and coral‐associated fishes, (3) Examined how macroalgae‐associated species can influence catch diversity, trophic level and vulnerability and (4) Explored how tropical fisheries change with the expansion of macroalgal habitats using a case study of fishery‐independent data for Seychelles. Fish that utilised macroalgal habitats comprise 24% of the catch, but very few fished species relied entirely on macroalgal or coral habitats post‐settlement. Macroalgal and coral‐associated fishes had similar life‐history traits, although vulnerability to fishing declined with increasing contribution of macroalgae association to the catch, whilst mean trophic level and diversity peaked when macroalgal‐associated fish accounted for 20%–30% of catches. The Seychelles case study revealed similar total fish biomass on macroalgal and coral reefs, although the biomass of primary target species increased as macroalgae cover expanded. Our findings reinforce that multiple habitat types are needed to support tropical fishery stability and sustainability. Whilst coral habitats have been the focus of tropical fisheries management, we show the potential for macroalgae‐associated fish to support catch size and diversity in ways that reduce vulnerability to overfishing. This is pertinent to seascapes where repeated disturbances are facilitating the replacement of coral reef with macroalgal habitats.

Using length data to derive biological reference points for kiddi shrimp Parapenaeopsis stylifera (Milne Edwards, 1837) from the south-eastern Arabian Sea, India

Parapenaeopsis stylifera, a major commercial penaeid shrimp fishery resource in the Indian Ocean, has lacked adequate information on life history parameters for nearly two decades. In this study, growth and mortality parameters of P. stylifera from the southwest coast of India were estimated using length data and used to derive biological reference points for the species. The asymptotic length for females was L∞ = 131 mm; k = 1.1 y−1 and for males L∞ = 117 mm; k = 1.25 y−1. Mortality parameter estimates were Z = 4.42, M = 1.24, F = 3.18 y−1 and exploitation rate E = 0.72 for females; Z = 5.76, M = 1.39, F = 4.37 y−1 and E = 0.76 for males. Thomson and Bell yield biomass, Beverton and Holt yield per recruit, and relative yield per recruit models were applied to predict the stock status and length cohort analysis for estimating the stock size. The Beverton and Holt analysis gave Emax = 0.69 in females and 0.75 for males, which is below the Ecurrent values obtained for the sexes. The Thomson and Bell analysis indicated that if Fcurrent at which the yield is 121 460 t in females and in males 128 064 t is further increased, rise in yield will be modest. B/B0 and SB/SB0 at Fcurrent were 24% and 18% for females and 21% and 16% for males, respectively. Target reference point F0.1 and F0.5 at different levels of age at capture tc (0.5, 0.6, 0.7 and 0.8 yrs) was estimated by Beverton and Holt yield per recruit model. The outcome from these models forms integral inputs for multispecies/multigear tropical fisheries management. Parapenaeopsis stylifera is one of the inshore penaeid shrimp identified by the Marine Stewardship Council for certification from the region and, moreover, biological reference points are a prerequisite to assessment and management of tropical multispecies fisheries for ecosystem-based fisheries management.

Participatory fishery monitoring is successful for understanding the reproductive biology needed for local fisheries management

Tropical fisheries management should rely on reproductive biology to inform management regulations; however, this information is often lacking and can be highly variable over in space and time. It is unfeasible for many fisheries, especially data-poor ones that are typical of tropical reefs to collect the necessary information on reproductive biology. One solution is a participatory approach where local fishers, scientists, and regulating agencies gather the necessary information to assess population variability for important management metrics such as size at maturity, reproductive output, and spawning seasons. Through collaborations with local fishers, we developed a monitoring program to gather population-level information on the reproductive characteristics of the convict tang, Acanthurus triostegus sandvicensis. We examined four locations across the main Hawaiian Islands and found size at maturity [size at which 50% of individuals are mature (L50)] to vary among locations, with interpopulation differences in maturity ~ 20% of the fish’s total length. Larger individuals produced more eggs and spawned more often than smaller individuals. A semilunar spawning pattern was observed, with group spawning occurring near the new and full moons. However this pattern was variable by year and location, likely resulting from different seasonal peaks in spawning by location. Gonadosomatic index (t = 2.41, p-value = 0.02) and spawning fraction (z = 2.92, p-value < 0.01) were both significantly higher in 2014 compared to 2013, suggesting annual variability in reproductive output. Participatory fishery monitoring proved successful in collecting biological needed for management and improved understanding of population reproductive variability.

Multi-criteria decision models for management of tropical coastal fisheries. A review

The crisis in the world’s fisheries is attributed to excessive fishing pressure, long-term mismanagement, increased population growth, development and improvement of fishing technologies, uncertainty in global fisheries catch data, economic incentives and subsidies, and increasing demand for fish meal. For the coastal fisheries of developing countries, the problem is aggravated by coastal habitat degradation, widespread poverty in coastal communities, inshore encroachment of commercial fishing vessels, use of illegal and destructive fishing methods, resource use conflicts, pollution from uplands, and weak institutional arrangements. In response to these problems and in the hope of reversing their negative effects, fisheries management strategies have emerged for tropical coastal fisheries during at least the past 30 years. In fisheries, it is crucial to determine the outcomes of management strategies, especially when public money has to be accounted for. However, efforts to assess their impacts or measure progress are usually directed towards a single disciplinary approach, which fails to consider the multi-dimensionality of tropical fisheries including concomitant multi-level and conflicting goals and objectives. This article explores the utility of a multi-criteria type of evaluation as a potential analytical approach in impact evaluation for tropical fisheries management. The general framework of a multi-criteria evaluation method is a two-dimensional matrix composed of different choice possibilities including the set of criteria and indicators that will serve as bases in assessing these choice possibilities. The literature presents various criteria and indicators in fisheries management evaluation, the kinds and number of which would depend on stated goals and objectives of fisheries and the availability of resources to acquire the information. The type of measurement, i.e., quantitative or qualitative, and the weighing of criteria and indicators are crucial in the evaluation process because they determine the multi-criteria aggregation approach to be used. Moreover, the participation of stakeholders and coastal resource users is crucial in complementing scientific information, in developing acceptable solutions, and in reducing conflicts and distrust in the evaluation and decision-making process. While many aggregation models in multi-criteria analysis in natural resource management exist, this article limits its review to only six models: the analytic hierarchy process, the weighted sum model, the ordination technique, concordance analysis, the regime method and Evamix; which are viewed to be applicable to the structure of decision-making in tropical fisheries management. This article also examines the performance of some of these models through a case study that determines the impacts of fisheries management strategies in San Miguel Bay, Philippines. The review reveals the following: (1) among the aggregation approaches, the analytic hierarchy process and ordination technique had the highest number of applications in fisheries while none was found for concordance analysis, the regime method or Evamix; (2) the application of hybrid models in multi-criteria analysis is increasing and found to be effective in many environmental decision problems including fisheries; (3) the application of multi-criteria decision models to fisheries management is relatively scarce during the last 10 years; only 26 papers were found in peer-reviewed journals; and (4) in the choice of model, its technical assumptions and limitations, its appropriateness for a specific decision-making problem, and its ability to handle the situation correctly vis-a-vis contextual, technical and political concerns should be considered.

Rapid assessment of community needs and fisheries status in tsunami-affected communities in Aceh Province, Indonesia

This paper describes the application of the methodology called Rapid Appraisal of Fisheries Management System (RAFMS) to assess quickly the situation in tsunami-affected coastal fisheries in Aceh Province, Indonesia. As a diagnostic tool, the RAFMS is introduced in terms of its conceptual framework and procedures. The RAFMS was used to appraise the status of the fisheries sector in selected 15 villages. Information generated concerning level of fishing effort, marketing patterns and community perspectives on livelihood options are used as three illustrative examples. The paper also provides some insights in applying the RAFMS methodology in the context of disasters and in the broader context of tropical fisheries management.

When Does this Fish Spawn? Fishermen’s Local Knowledge of Migration and Reproduction of Brazilian Coastal Fishes

Fishermen’s local knowledge of fishing resources may be an important source of information to improve artisanal tropical fisheries management, such as those found in Brazil, where most data on fish biology is lacking. We aim to study the local ecological knowledge that Brazilian coastal fishers have about reproductive aspects (season, places and migration) of 13 coastal fish species of commercial importance. We selected fishermen with more than 30 years of fishing practice and we interviewed a total of 67 fishermen: 29 from the southeastern coast, from the communities of Puruba, Almada, Picinguaba and Bertioga, and 38 from the northeastern coast, from the communities of Valenca, Arembepe and Porto Sauipe. In the interviews, we used standardized questionnaires and showed photos of fish species. Our results indicate some general patterns in fishes’ reproduction according to fishermen knowledge: fish species spawn in open ocean, near reefs or in coastal rivers (estuaries); some fishes reproduce during the summer and others in winter, while some have more defined spawning months. The main fish migratory patterns mentioned by interviewees were: long migrations along the coast, usually in the South to North direction, short migrations among reefs, fishes that do not migrate, migrations between the shore and open ocean and migrations between the sea and coastal rivers. Fishermen’s knowledge differed among fish species: most fishermen did not know spawning places or seasons of large pelagic fishes, which raised concerns of their possible depletion. We compared such ethnoichthyological information with available scientific data, indicating promising insights about reproduction and migration of Brazilian coastal fishes. Data gathered from local fishermen may provide inexpensive and prompt information, potentially applicable to fisheries management. Our approach might be useful to several other small-scale fisheries, especially the tropical ones, where there is a high diversity of target species and a low biological and ecological knowledge about these species.

How the uncertain outcomes associated with aquatic and land resource use affect livelihood strategies in coastal communities in the Central Moluccas, Indonesia

Management of tropical fisheries often fails because of a limited sectoral approach that disregards the livelihoods of small-scale fishermen. Fishermen are viewed as specialists, although many fisheries cannot provide an income that is large and stable enough to allow for such specialisation. The economic outcome of the enterprise is linked to the production patterns of the resource, and the dynamics of the resource affect the livelihood strategies of the people exploiting these resources. The limiting factors for specialisation in four enterprises exploiting natural resources (purse-seine fishery, sago extraction, nutmeg and clove cultivation) were studied in terms of size, patterns and uncertainty in production and income in the coastal community on Ambon and the Lease Islands (Moluccas, Indonesia). This was done for labourers and owners of fishing gear and land. Only owners of purse-seine vessels have sufficient mean income to maintain their families (27.5 rice equivalents per day), although the basic uncertainty in their daily income is extremely high (CV=410%). For owners of the other three enterprises income is not enough to maintain a household, because of the small scale of the production units, being only tens of trees. For labourers, the daily incomes from fishing and sago extraction are too low (mean income=3.2 and 4.1 rice equivalents per day) to maintain their households of six members at the poverty level (0.88 rice equivalents per capita per day), although both activities can be practised almost year round. Moreover, daily income for labourers from the fishery is highly uncertain because of the uncertainty in daily catches (CV=220%), which is not reduced by price compensation. Although the sharing system reduces the basic uncertainty in the daily income of labourers, the resulting income is still highly uncertain, ranging from 0 to 78 rice equivalents per day (CV=170%). Mean daily income from nutmeg and clove picking are several times higher (8.4 and 13.9 rice equivalents per day), but because of the limited temporal availability of these resources (roughly two months per year for both spices), they cannot provide enough income to maintain a household. The low income and high uncertainty for the labourers involved mean that the purse-seine fishery cannot provide a stable basic income: to stabilise it, other sources of income are needed. This has consequences for many characteristics of the fishery, such as the large proportion of part-time fishermen, the allocation of fishing effort and the type of technical innovations implemented in the fishery.

BOOK REVIEWS

Book Reviwed in this article:FISH PHYSIOLOGY. VOLUME 9–PART A AND VOLUME 9–PART B, REPRODUCTION. Edited by W. S. Hoar &amp; D. J. RandallMARINE NATURAL PRODUCTS, CHEMICAL AND BIOLOGICAL PERSPECTIVES, VOLUME 5. Edited by Paul J. ScheuerQSAR IN ENVIRONMENTAL TOXICOLOGY. Edited by K. L E. KaiserTHEORY AND MANAGEMENT OF TROPICAL FISHERIES. Edited by D. Pauly &amp; G. I. Murphy

Book Review

Books reviewed in this article:Theory and Management of Tropical Fisheries. Ed. by D. Pauly &amp; G. I. Murphy.

Book reviews

Theory and management of tropical fisheries. Edited by D. Pauly and G. I. Murphy. Proceedings of the ICLARM/CSIRO Workshop on the Theory and Management of Tropical Multispecies Stocks. 12–21 January 1981, Cronulla, Australia. 1982. 360 p. $US21.50 surface; hardbound. Animals of the estuary shore : illustrated guide and ecology. By Malcolm B. Jones, 1983. University of Canterbury publication No. 32. 162p., 140 figures, 11 keys. ISBN 0900–392–32–0 (soft cover, spiral bound). Price NZ$7.50. Numerical ecology. By L. Legendre and P. Legendre, 1983. Elsevier Scientific Publishing Company, Amsterdam. $US83.00. The control of oil pollution (revised edition). Edited by J Wardley‐Smith. Graham & Trot‐man Limited, London. 1983. 285 p., 98 figures, 17 tables. ISBN 0.86010 3382. £19.00/$US35.00. Physical oceanography in Australia. Edited by J. Imberger. Reprinted from the Australian Journal of Marine and Freshwater Research, Volume 34, 1–230, 1983. CSIRO, Melbourne 1983.