The statistical properties of recreational catch rate data for some fish stocks off the northeast U.S. coast

Recreational fisheries in the waters off the northeast U.S. target a variety of pelagic and demersal fish species, and catch and effort data sampled from recreational fisheries are a critical component of the information used in resource evaluation and management. Standardized indices of stock abundance developed from recreational fishery catch rates are routinely used in stock assessments. The statistical properties of both simulated and empirical recreational fishery catch-rate data such as those collected by the National Marine Fisheries Service (NMFS) Marine Recreational Fishery Statistics Survey (MRFSS) are examined, and the potential effects of different assumptions about the error structure of the catch-rate frequency distributions in computing indices of stock abundance are evaluated. Recreational fishery catch distributions sampled by the MRFSS are highly contagious and overdispersed in relation to the normal distribution and are generally best characterized by the Poisson or negative binomial distributions. The modeling of both the simulated and empirical MRFSS catch rates indicates that one may draw erroneous conclusions about stock trends by assuming the wrong error distribution in procedures used to developed standardized indices of stock abundance. The results demonstrate the importance of considering not only the overall model fit and significance of classification effects, but also the possible effects of model misspecification, when determining the most appropriate model construction.

Marine fish assemblages associated with fish aggregating devices (FADs): effects of fish removal, FAD size, fouling communities, and prior recruits

Fishes are widely known to aggregate around floating objects, including flotsam and fish aggregating devices (FADs).The numbers and diversity of juvenile fishes that associated with floating objects in the nearshore waters of the eastern tropical Pacific were recording by using FADs as an experimental tool. The effects of fish removal, FAD size, and the presence or absence of a fouling community at the FAD over a period of days, and the presence of prior recruits over a period of hours were evaluated by using a series of experiments. The removal of FAD-associated fish assemblages had a significant effect on the number of the dominant species (Abudefduf troschelii) in the following day’s assemblage compared to FADs where the previous day’s assemblage was undisturbed; there was no experimental effect on combined species totals. Fishes do, however, discriminate among floating objects, forming larger, more species-rich assemblages around large FADs compared to small ones. Fishes also formed larger assemblages around FADs possessing a fouling biota versus FADs without a fouling biota, although this effect was also closely tied to temporal factors. FADs enriched with fish accumulated additional recruits more quickly than FADs that were not enriched with fish and therefore the presence of prior recruits had a strong, positive effect on subsequent recruitment. These results suggest that fish recruitment to floating objects is deliberate rather than haphazard or accidental and they sup-port the hypothesis that flotsam plays a role in the interrelationship between environment and some juvenile fishes. These results are relevant to the use of FADs for fisheries, but emphasize that further research is necessary for applied interests.

Toxicity of phenyl-mercuric lactate for fish

Phenyl-mercuric lactate is included in the pulp processing reagents by some paper mills to eliminate slime formation in the pulp. Small quantities of this chemical are added to the wet pulp in the beaters, particularly for the bactericidal action against Aerobacter aerogenes. Subsequently the mecurial is carried away in the wash waters. However, as the highly poisonous nature of many compounds of mercury is well known, questions have been raised concerning the pollution hazards created by phenyl-mercuric lactate in streams receiving effluents from mills using this substance.

Fish for the future: Fisheries development and food security for Kiribati in an era of global climate change

The Republic of Kiribati is a vast South Pacific island group with one of the largest exclusive economic zones (EEZs) in the world. Kiribati waters support a wealth of marine fisheries activities. These activities occur in oceanic, coastal and inshore environments and range from large, foreign, industrial-scale oceanic fishing operations to small-scale, domestic, inshore subsistence fisheries, aquaculture and recreational fisheries. Kiribati has developed a framework of domestic and international governance arrangements that are designed to sustainably manage its wealth of marine resources. The report provides background information for fisheries projects in Kiribati that aim to build food security, improve artisanal livelihoods and strengthen community engagement in fisheries governance. It provides information on the current status of Kiribati fishery resources (oceanic and coastal), their current governance and future challenges. Fish and fisher alike pay little heed to maritime boundaries and bureaucratic distinctions. This report covers both sides of the oceanic/coastal boundary because of the I-Kiribati communities’ interest in oceanic fisheries such as tuna and their heavy dependence on its fisheries resources for food security and economic development. The report focuses on two potential pilot sites for community-based fisheries management projects: North Tarawa and Butaritari.

Informal fish retailing in rural Egypt: Opportunities to enhance income and work conditions for women and men

Poor rural consumers benefit from Egypt’s aquaculture sector through access to small and medium-sized farmed tilapia sold by informal fish retailers, many of whom are women. In fact, informal fish retail is the main, if not only, segment of the farmed fish value chain where women are found. This report aims to inform current and future strategies to improve conditions in informal fish retail by understanding in more depth the similarities and differences in employment quality and outcomes across different fish retailers. It is particularly focused on identifying whether and how gender inequality influences different dimensions of the work, and whether women and men have similar outcomes and employment conditions. This knowledge will help to design interventions to overcome gender-based constraints, as well as approaches that address shared obstacles and include both women and men in gender-responsive ways to ensure that all of those involved in the sector benefit.

A study on length-weight relationship, food and feeding habits of Indian scad, Decapterus russelli (Ruppel, 1830) along the northwest coast of India

Length and weight relationship of Decapterus russelli (Ruppell, 1830) is worked out to be W = 0.00312 L³ which indicates the isometric growth of the fish. Study on food and feeding habits revealed that the species is carnivorous, pelagic, feeding primarily on small crustaceans and small fish species, viz. Acetes indicus, ostracods, Apogon sp., Leiognathus sp., sciaenids, Netnipterus japonicas, Myctophid sp., Trichiurus sp., Therapon sp., D.russelli and occasionally on prawns. It is a selective feeder on Aeetes indicus.

Predatory behaviour of a snakehead fish (Channa striatus Bloch)

The predatory behaviour of a snake-head, Channa striatus (Bloch) on Labeo rohita fingerlings was studied in the laboratory. The study was conducted with six C. striatus (120 to 210 g and 22 to 28 cm) over 24h a day for 3 weeks. Three different sizes prey of large (2.00g and 5.8cm), medium (1.30g and 4.5cm) and small (0.72g and 3.5cm) were used for the first week and then medium size prey for 2nd and 3rd weeks. All the predators preferred eating the small group of L. rohita although all three size groups of L. rohita offered were available. It was found that the prey fishes remained together aside of the aquarium from the predator. Predator first targeted a prey, drove fast towards it, the prey tried to escape from the predator's attack using a specific route and finally the predator grasped the prey on head first and then engulfed. The handling time ranged between 45 and 50 sec. The time of peak feeding was found in the morning and in the evening of day. When 2 or 3 predators were kept in one aquarium, they engaged in fighting, head on, followed by an attack on the mouth region by the dominant one, and subsequently on the pectoral fin and caudal fin of the defeating one. After 2-3 days they became habituated to remain together and did not involve themselves in fighting.

Preliminary observations on the effect of electrical seine on fish catch

Forty-six experiments were done with the electric seine in 24 tanks with a.c. and interrupted a.c. The source of electrical energy was a 3 Kw a.c. generator of water-cooled diesel engine. A control seining without applying electricity was conducted for every experiment with electric "seine" to have a comparison for the efficiency of electric "seine" over control ones. Electric seine was found to have an increased catch over control seining both in numbers and in weight. Electric seine with two electrodes was found to have better effect over three electrodes. Benthic fishes like Cirrhina mrigala, Notopterus notopterus, Cyprinus carpio, Glassogobius giuris, Ophicephalus sp. and Mystus sp. were found to be more sensitive in electric "seine". Increased catch of small fishes like C. mrigala, N, notopterus and Ophicephalus sp. has been observed in electrical "seine" in addition to larger ones.

Rearing of Labeo bata in sewage-fed fish culture pond

Labeo bata is a highly priced fish which commanding good consumer preference, even if the size is very small (15 to 20 g each), especially in West Bengal. With a view to evaluating the culture potential of this fish, repeated experiments were conducted at the Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara, West Bengal, during 1991-93 in ponds fed with treated domestic sewage effluent. An average production of 1270.63 kg per ha was obtained within 6 to 10 months for a uniform stocking density of 50,000 seed per ha. The average size attained by the fish in the different sets of experiments varied from 23.3 to 37.9 g as against the initial weight of 0.096 to 0.193 g. Details of management, growth, survival, quantity of sewage used and pond nutrient status and productivity are dealt with in this communication.

Coastal fisheries

The coastal zone of Sri Lanka is the most important area of fish production at present. This coastal zone is limited seawards to the edge of our relatively narrow continental shelf. The fishing methods employed are such that only a fraction of the shelf area is exploited. The extent to which the coastal zone is exploited depends on the craft and gear used in the fishing operations. The non-mechanized traditional crafts such as the teppams and orus generally operate within about five miles from shore. The mechanized traditional crafts and the small mechanized boats introduced around 1957 carry out fishing operations up to the continental shelf or beyond. The gear used by these fishing crafts is determined by the habits of the type of fish to be caught, the nature of the sea bed and other related conditions. For the pelagic fishes they use trolling lines or float long lines or drift nets. For the demersal fishes hand lines, bottom long lines, bottom set nets or drag nets are used. However, the net is the preferred fishing gear. The beach seines or madels, the traditional crafts such as orus, teppams and vallams and the small mechanized boats are the important contributors in the coastal fishery. Of these the madels are considered the most important since a high percentage (25-35%) of the Island's landings are produced by the operation of these nets.

Small mesh trawling

Experimental trawling operations for bottom fish were first begun in 1920 and consisted of surveys of the continental shelf around Ceylon and the west and east coasts of India. These preliminary surveys showed that the continental shelf of Ceylon was either very poor in bottom fish or that the ground was so rough that trawling has proved to be economically not sustainable (Malpas, 1926). Although a considerable amount of trawling has been carried out using small-meshed trawls, there is no record of the details of the gear used or any account of the relative efficiency of the different designs of trawls used in the operations. Experimental operations were, therefore, carried out off 80 h.p. boats such as m.f.v. Canadian and North Star, to select the most effective gear for these boats. In more recent times experiments were also conducted to select the most effective trawling gear for the 11-Ton boats of the Ceylon Fisheries Corporation. The results are reported in this publication.

A short note on the available information about demersal fish on the shallow part of Sofala Bank

The present information on the biomass and catch of demersal species which constitute a large part of the by-catch of the shrimp trawlers on the Sofala Bank (Mozambique), and thus seem to be more vulnerable than the pelagic stocks to an increase in effort is described. In addition, preliminary data on growth and mortality of two demersal species, Johnius belengerii and Otolithes ruber , which are frequently found in the by-catch, is presented.

Rights first, rights forever: small-scale fisheries and fishing communities from a human-rights perspective. A collection of articles from SAMUDRA report

Small-scale and artisanal fisheries contribute about two-thirds of the global fish production destined for direct human consumption. They also accommodate over 90 per cent of those who make their living from fisheries. Women comprise at least half the workforce in small-scale fisheries. Despite the important contributions made by small-scale fisheries to poverty eradication and food security, small-scale fishers and fishworkers continue to be marginalized at different levels. It is in this context that the Committee on Fisheries (COFI) of the Food and Agriculture Organization of the United Nations (FAO) has developed the Voluntary Guidelines for Securing Sustainable Small-scale Fisheries in the Context of Food Security and Poverty Eradication (SSF Guidelines).

Hydrology and fish distribution at the Sofala Bank (Mozambique)

A brief review is made of the hydrologic conditions at the Sofala Bank, mainly based on the research data obtained from 1978 to 1982. A description is attempted of the circulation pattern and the distribution of water masses in the area, four hydrologic regimes being identified. These are compared with the distributions of different pelagic and demersal fish species. A tendency is found for different groups of species to prefer different hydrologic regimes.

Economics of pond fish culture in some selected areas of Bangladesh

A simple costs and return analysis was done to determine the profitability of pond fish culture in three selected thanas namely Nertakona Sadar, Purbadhala and Kendua under Netrakona district. Cobb-douglas production function model was used to estimate the contribution of key variables to the production process of pond fish culture. It was found that cost of pond fish production was Tk. 10,103/ha/yr and the per hectare fish yield was 943 kgl/yr and the average gross and net return were Tk. 49,515 and Tk. 39,412 respectively. It was found that medium and small farms had the higher yield because of efficient use of production inputs compared to large farms. It was also observed that ownership of pond, number of species and human labour had negative impact on pond fish output, while depth of pond water, farm size, fish seed, fertilizer and artificial feed had significant positive effects on pond fish output.