983 resultados para Reproductive Strategies


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The 1984 International Symposium and Workshop on the Biology of Fur Seals originated in informal talks in 1981. However, the scope and focus of the symposium remained unclear until an informal workshop was held in San Diego in June 1983. This meeting synthesised data on the foraging and pup attendance activities of six species of fur seals, and attempted to formulate a coherent framework for the adaptations associated with their maternal strategies (Gentry et al. 1986). During the workshop it was clear that comparative data on many key aspects of fur seal biology and ecology were missing. This absence of data applied not only to less well known species, for some of which considerable unpublished data existed, but also to better known species for which research in some areas had either been neglected or unreported. The value of applying the comparative method to seals, especially comparisons integrating physiology, ecology, and reproductive biology, was amply demonstrated by the results of the 1983 workshop (Gentry and Kooyman 1986). However, we were also aware that many other problems outside the area of maternal strategies could benefit from comparative data, such as recovery of populations from the effects of harvesting. Therefore, to accommodate the range of potential research, we organized this symposium to produce an up-to-date synthesis of relevant information for all species of fur seals. It was also clear that fur seal research could benefit from increased communication and collaboration among its practitioners. To foster the spread of ideas, we held oral presentations on some topics of current research and techniques and organized workshops on specific topics, in addition to providing opportunities for informal talks among participants. Thanks to generous support from the British Antarctic Survey, the National Marine Fisheries Service of the United States, and the Scientific Committee on Antarctic Research, the International Fur Seal Symposium was held at the British Antarctic Survey, Cambridge, England, 23-27 April 1984. The 36 participants are shown in Figure 1. A list of Symposium participants and authors is presented in Appendix 1 of the Proceedings. (PDF file contains 220 pages.)

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Venomous Indo-Pacific lionfish (Pterois miles and P. volitans) are now established along the Southeast U.S.A. and parts of the Caribbean and pose a serious threat to reef fish communities of these regions. Lionfish are likely to invade the Gulf of Mexico and potentially South America in the near future. Introductions of lionfish were noted since the 1980s along south Florida and by 2000 lionfish were established off the coast of North Carolina. Lionfish are now one of the more numerous predatory reef fishes at some locations off the Southeast U.S.A. and Caribbean. Lionfish are largely piscivores that feed occasionally on economically important reef fishes. The trophic impacts of lionfish could alter the structure of native reef fish communities and potentially hamper stock rebuilding efforts of the Snapper –Grouper Complex. Additional effects of the lionfish invasion are far-reaching and could increase coral reef ecosystem stress, threaten human health, and ultimately impact the marine aquarium industry. Control strategies for lionfish are needed to mitigate impacts, especially in protected areas. This integrated assessment provides a general overview of the biology and ecology of lionfish including genetics, taxonomy, reproductive biology, early life history and dispersal, venom defense and predation, and feeding ecology. In addition, alternative management actions for mitigating the negative impacts of lionfish, approaches for reducing the risk of future invasions, and directions for future research are provided.

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Sources of fish and fishery products in Nigeria were reviewed. The problems of various agencies involved in freshwater fish production in Nigeria were also analysed, such problems included shortage of manpower, inadequate training for personnel, shortage of funds, lack of infrastructures, among others

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There is increasing awareness of aquaculture in Nigeria today for a number of reasons namely: water pollution, declining catch and the awareness of the attractiveness of aquaculture as an investment area and a pivotal point for national development. The development of aquaculture in Nigeria, requires the building up of institutions at the grassroot level and the formulation of policies and programmes for the small fishfarmer. This of course would be backed up by a sound technology generation, verification and packaging, dissemination and use programme

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Cost projections for the establishment of a fish farm in Nigeria was conducted. It is shown that fish farming should be a lucrative venture. However, many private fish farms are not making the desired profits because of a variety of problems. Besides managerial incompetence, availability of fingerlings for stocking in the ponds is shown to be a serious handicap to the success of investments in a fish farm. It is suggested that where the funds are available, each farm should be equipped with facilities for raising its needs of fingerlings. Since useful capital would be involved and knowledgeable experts to run the hatcheries are few, it is recommended that fish farms within a state or adjacent states should combine to establish viable cooperative hatcheries

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An examination is made of the socio-economic factors associated with the failure of existing approaches to the fishing input requirements of small-scale fisheries in Nigeria. The fishermen and secretaries of the fishermen cooperative societies in three major settlements (Uta-Ewa, Okoroete and Iko) were selected for interviews. The survey showed that the idealogy of the fishermen of the role of cooperative society is wrong and specific programmes need to be directed towards correcting this perception. Thus, for any meaningful support programme for the artisanal small-scale fishermen, the perception of the fishermen about the cooperative organization must first be aligned rightly. It is suggested that the fishing input be determined by type and specification as a preliminary step in the delivery of inputs to the fishermen. Social, economic and cultural variabilities should be related to the requirement by the fishermen. The price level of fishermen will determine the direction and level of government support required

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(PDF contains 94 pages.)

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Aspects of the reproductive biology of Mugil cephalus in the Bonny estuary (Nigeria) were studied between January and December 1996. Males were observed to be more slender than females while the females have deeper bodies. The male:female ratio (1:0:95) was not significantly different. The minimum size at maturity was 16.6cm (0.5 yr). Fish matured at 24.3cm TL(1.76 yr) with median maturity size of 19.5cm TL(0.71 yr). Median maturity for male and female fish were 16.4cm TL(0.41 yr) and 18.2cm TL(0.60 yr) respectively. Breeding occurred once a year between September and December, from late rainy season to early dry season. Mean absolute fecundity was 1,403, 808 eggs (range 107, 729-4,445, 423 eggs) for fish of 17.0.29.5cm TL (mean 22.5cm TL). Fecundity correlated positively with fish total weight, length, ovary weight and age

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The present corpus study aimed to examine whether Basque (OV) resorts more often than Spanish (VO) to certain grammatical operations, in order to minimi ze the number of arguments to be processed before the verb. Ueno & Polinsky (2009) argue that VO/OV languages use certain grammatical resources with different frequencies in order to facilitate real-time processing. They observe that both OV and VO languages in their sample (Japanese, Turkish and Spanish) have a similar frequency of use of subject pro-drop; however, they find that OV languages (Japanese, Turkish) use more intransitive sentences than VO languages (English, Spanish), and conclude this is an OV-specific strategy to facilitate processing. We conducted a comparative corpus study of Spanish (VO) and Basque (OV). Results show (a) that the fre- quency of use of subject pro-drop is higher in Basque than in Spanish; and (b) Basque does not use more intransitive sentences than Spanish; both languages have a similar frequency of intransitive sentences. Based on these findings, we conclude that the frequency of use of grammatical resources to facilitate the processing does not depend on a single typological trait (VO/OV) but it is modulated by the concurrence of other grammatical feature.

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Sarotherodon galilaeus and Oreochromis niloticus are 2 readily available fish species in Nigeria, often cultured interchangeably. The findings are presented of a comparative study conducted to provide information on their performance using similar nutrient loadings without supplemental feed. Results showed a better performance of O.niloticus over S.galilaeus, which may be partly explained by the dietary mechanisms of the fish. Further trials on gut content analyses are required