356 resultados para marine organisms
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Marine crabs belonging to the family Portunidae form bycatch of shrimp trawlers in India. They are sold at low prices and consumers discard eggs and consume the meat. The paper details the nutritional value of eggs of Portunus pelagicus.
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The article highlights briefly the economics of different types of fishing units operating along the Indian coast; analyzes the exploitation trend of major marine fishery resources in relation to its potential yield; and suggests policy measures for optimum exploitation of resources, conservation and management.
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Vibriosis caused by opportunistic and secondary bacterial pathogens is still a serious disease problem in aquaculture of the black tiger shrimp Penaeus monodon. Attempts were made for controlling shrimp bacterial disease using Marine Secondary Metabolites (MSMs). Findings indicated that the MSMs of seaweed Ulva fasciata and Dendrilla nigra are effective for controlling shrimp bacterial pathogens.
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This paper presents 649 length-weight relationships gathered from literature pertaining to 83 fish species, belonging to 34 families, throughout Greek marine waters. The value of the slope b ranged from 1.667 for Cepola macrophthalma to 3.707 for Mullus barbatus. The mean value of b was 2.989 (SD=0.339) and did not differ significantly from 3(t-test, p<0.05). The median value of b was 3.058 and 50% of the b values ranged between 2.900 and 3.186.
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Three different trials for the experimental culture of marine copepods (Acartia purmosa) are presented. The potential of the species as live foods in fish hatcheries are also discussed.
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To help reverse the downward trends for the world's marine fish stocks, the Worldwide Fund for Nature (WWF) and the Aglo-Dutch Unilever have jointly formed the Marine Stewardship Council (MSC), an independent, non-profit, non-governmental membership body. The rationale and strategies to achieve the goals of the joint effort are discussed.
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Video technology has been used as a tool in research for many years. However, its widespread use as a fisheries management tool has been limited due to its relatively high cost. This is changing as video technology becomes a household commodity now widely available throughout the world.
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A total of 73 sets of growth parameters for 34 species belonging to 12 families of marine fish caught in Cuban waters are presented. These parameters are compiled from existing studies (58 sets) or derived from data obtained in the original literature (15 sets).
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The highly productive fisheries of Kerala, India, are suffering from overexploitation. Use of unsuitable fishing gears that result in a high level of wasteful bycatch and destruction of egg bearing and juvenile fish should be controlled. This paper makes some suggestions for monitoring and conservation of the fisheries in Kerala.
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Water currents are vertically structured in many marine systems and as a result, vertical movements by fish larvae and zooplankton affect horizontal transport (Power, 1984). In estuaries, the vertical movements of larvae with tidal periods can result in their retention or ingress (Fortier and Leggett, 1983; Rijnsdorp et al., 1985; Cronin and Forward, 1986; Forward et al., 1999). On the continental shelf, the vertical movements of organisms interact daily and ontogenetically with depth-varying currents to affect horizontal transport (Pillar et al., 1989; Barange and Pillar, 1992; Cowen et al., 1993, 2000; Batchelder et al., 2002).
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The carpenter seabream (Argyrozona argyrozona) is an endemic South African sparid that comprises an important part of the handline fishery. A three-year study (1998−2000) into its reproductive biology within the Tsitsikamma National Park revealed that these fishes are serial spawning late gonochorists. The size at 50% maturity (L50) was estimated at 292 and 297 mm FL for both females and males, respectively. A likelihood ratio test revealed that there was no significant difference between male and female L50 (P>0.5). Both monthly gonadosomatic indices and macroscopically determined ovarian stages strongly indicate that A. argyrozona within the Tsitsikamma National Park spawn in the astral summer between November and April. The presence of postovulatory follicles (POFs) confirmed a six-month spawning season, and monthly proportions of early (0−6 hour old) POFs showed that spawning frequency was highest (once every 1−2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature (r = −0.161), the daily proportion of spawning fish was strongly correlated (r= 0.93) to ambient temperature over the range 9−22oC. These results indicate that short-term upwelling events, a strong feature in the Tsitsikamma National Park during summer, may negatively affect carpenter fecundity. Both spawning frequency and duration (i.e., length of spawning season) increased with fish length. As a result of the allometric relationship between annual fecundity and fish mass a 3-kg fish was calculated to produce fivefold more eggs per kilogram of body weight than a fish of 1 kg. In addition to producing more eggs per unit of weight each year, larger fish also produce significantly larger eggs.
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Recent research demonstrated significantly lower growth and survival of Bristol Bay sockeye salmon (Oncorhynchus nerka) during odd-numbered years of their second or third years at sea (1975, 1977, etc.), a trend that was opposite that of Asian pink salmon (O. gorbuscha) abundance. Here we evaluated seasonal growth trends of Kvichak and Egegik river sockeye salmon (Bristol Bay stocks) during even- and odd-numbered years at sea by measuring scale circuli increments within each g rowth zone of each major salmon age group between 1955 and 2000. First year scale growth was not significantly different between odd- and even-numbered years, but peak growth of age-2 smolts was significantly higher than age-1. smolts. Total second and third year scale growth of salmon was significantly lower during odd- than during even-numbered years. However, reduced scale growth in odd-numbered years began after peak growth in spring and continued through summer and fall even though most pink salmon had left the high seas by late July (10−18% growth reduction in odd vs. even years). The alternating odd and even year growth pattern was consistent before and after the 1977 ocean reg ime shift. During 1977−2000, when salmon abundance was relatively great, sockeye salmon growth was high during specific seasons compared with that during 1955−1976, that is to say, immediately after entry to Bristol Bay, after peak growth in the first year, during the middle of the second growing season, and during spring of the third season. Growth after the spring peak in the third year at sea was relatively low during 1977−2000. We hypothesize that high consumption rates of prey by pink salmon during spring through mid-July of odd-numbered years, coupled with declining zooplankton biomass during summer and potentially cyclic abundances of squid and other prey, contributed to reduced prey availability and therefore reduced growth of Bristol Bay sockeye salmon during late spring through fall of odd-numbered years.
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Sources of wastes in fishing operations mainly include bycatch discards; processing wastes where catch is processed onboard; plastic wastes due to abandoned, lost and discarded fishing gear; bilges and other wastes from the vessel operations. Fishing systems in general have an associated catch of nontargeted organisms known as bycatch. Non-selective fishing gear that is not modified or equipped to exclude non-targeted organisms, may take a significant quantity of bycatch of non-targeted finfish, juvenile fish, benthic animals, marine mammals, marine birds and vulnerable or endangered species that are often discarded. Average annual global discards, has been estimated to be 7.3 million t, based on a weighted discard rate of 8%, during 1992-2001 period. Trawl fisheries for shrimp and demersal finfish account for over 50% of the total estimated global discards. Plastic materials are extensively used in fisheries, owing to their durability and other desirable properties, contributing to the efficiency and catchability of the fishing gear. However, plastics biodegrade at an extremely slow rate compared to other organic materials. Abandoned, lost or otherwise discarded fishing gear (ALDFG) and related marine debris have been recognized as a critical problem in the marine environment and for living marine resources. Prevention of excess fishing capacity by appropriate management measures could lead to enormous savings in terms of fuel consumption, emissions and bycatch discards from the excess fishing fleet, capital and operational investments and labour deployment in capture fisheries, with significant economic gains. In this paper, wastes originating from fishing operations are reviewed, along with their environmental impacts and possible mitigation measures
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The United States has managed and analyzed its marine fisheries since 1871, and since 1970 via NOAA’s National Marine Fisheries Service (NMFS). As the primary directive moved from aiding fishermen in expanding their operations emphasizing conservation, the government over time recognized that management involves influencing people not fish, and has hired social scientists to complement the biologists who assess fish populations. This change has not always been smooth. We use archival documents and oral histories to trace the development of sociocultural analytic capabilities within NMFS and describe future plans for growing the program. Four points are made. First, NMFS has created the best developed social science program in NOAA. Second, established institutions change slowly; achieving the social science presence in NMFS has taken over 25 years. Third, change needs visionaries and champions with both tenacity and opportunity. Fourth, social science data collection and research helps in making fishery management decisions, but they have also been useful in evaluating the impact and helping with the recovery from Hurricane Katrina. Good work finds other uses.
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Geographic Information Systems can help improve ocean literacy and inform our understanding of the human dimensions of marine resource use. This paper describes a pilot project where GIS is used to illustrate the connections between fish stocks and the social, cultural, and economic components of the fishery on land. This method of presenting and merging qualitative and quantitative data represents a new approach to assist fishery managers, participants, policy-makers, and other stakeholders in visualizing an often confusing and poorly understood web of interactions. The Atlantic herring fishery serves as a case study and maps from this pilot project are presented and methods reviewed.