Effect of different sex ratios of ablated wild-stock Penaeus monodon Fabricius on maturation, fecundity and hatching rates

The study was conducted to determine other sex ratios of ablated wild-stock Penaeus monodon other than the most commonly practiced 1 male: 1 female. Four different sex ratios, 0:1, 1:1, 1:2, and 1:4 male: female were tested in four 4m diameter circular tanks for a period of 55 days. During the first run the 1 male: 2 females ratio gave: (a) the highest percentage of first (42.20%), second (30.00%) and third (33.33%) spawning; and (b) the highest total and average fecundity (3.9 million eggs and 300,692 eggs, respectively). The 1 male: 2 females ratio is recommended on the basis of highest percentage for the first, second and third spawners, total and average fecundity.

Population dynamics and stock assessment of the common carp (Cyprinus carpio) in Iranian waters of the Caspian Sea

In order to come up with the responsible fishing pattern of common carp, there was a need to identify some of the biological characteristics and stock assessment of carp in Iranian waters of the Caspian Sea .The fork length ,weight ,age ,growth parameters of von bertalanffy and mortality rates of common carp were estimated from oct 2006 to sept 2007.Based on the exponential relationship between length and weight in the size range 6.3-65.6 cm ,b was calculated 2.895, 2.843 and 2.925 respectively for combined sexes ,males and females. The mean condition factor was 1.9 which is close to the ideal condition.The results from measuring 3170 specimens ,were showed the first fork length of maturity was 30 cm for males and 32 cm for females. The results indicated that females were predominate and sex ratio was 0.66:1 (M:F) and chi-squares analysis showeda significant difference between males and females.(p<0.05).Length infinity and growth coefficient were calculated by three different methods as below: Length frequency analysis : k=0.17 L∞ =68.04 Age-Length Key k=0.15 L∞ =74.25 Back calculation : k=0.14 L∞ =68.4 The mortality parameters and exploitation rate were estimated as below : Z=0.73 per year M=0.31 per year F=0.42 per year E=0.56 Refer to amount of common carp catch in 2007 -08 ,biomass was calculated 9640.2 tones by jone's cohort analysis and MSY 2374.5 tones.According to analysis ,the number of common carp in the distribution area (Iranian part of the Caspian Sea ) was estimated 24 millions in the 2006-07.

Genetic study on breeding stock of the Indian mackerel along the Indian coast

The study included: sample collection; microsatellite genotyping and analysis; and preliminary results

Stock structure of Indian mackerel in Sri Lankan coastal waters

The objective of the project was to determine the stock structure of Indian Mackerel (Rastrelliger kanagurta) using microsatellite analysis

Dispersion, population dynamics and stock assessment of Caspian Sea prawns, genus Palaemon in Guilan Province coastal waters

Biological aspects, population dynamics and stock assessment of the Caspian Sea prawns Palaemon adspersus and Palaemon eleganse were investigated in Guilan coastal water of the Caspian Sea. Sampling was done monthly with a bottom trawl with mesh size of 3 mm in cod end in 0 - 5 m and 5 - 10 m depth in areas as Astra, Shafa Roud, Anzali, Chonchanan Chamkhaleh and Chaboksar during year 2002. Results of one year sampling showed that mean total length of Palaemon adspersus (pooled data) was 39.9±6.84 mm (X±SD) and mean wiegth was 1.133±0.67 g. The mean total length of females and males was 41.6±7.5 mm and 37.9±5.2 mm respectively and mean weight for the mentioned sexes was 1.353±0.65 g and 0.868±0.38 g respectively. There was significant differences in mean length and weight of females and males (P<0.05). The mean total annual sex ratio of males: females for this species was 1.4 and this sex ratio deviated significantly from 1:1 (X2, P<0.05) and biased towards males in the population of this species. The spawning season of Palaemon adspersus begins in April and ends in September with a peak in June . Mean fecundity of this species was 1994.5 ± 506.6 . The growth coefficients Loo and K for females were estimated as 58.5 mm and 2.3 /Year and for males as 55.9 mm and 2.6 /year respectively . The mean CPUA ( catch / Km2 ) for this species was 9.99 ± 33.2 kg / km2 and the correspondance biomass was calculated as 5067.7 kg in 0 - 10 m depth . The mean total length of Palaemon elegans (pooled data ) was 27.5 ± 5.7 mm (X±S.D) and mm and 24.01±4.18 mm respectively and mean weight for the mentioned sexes were was 0.553 ± 0.3 g and 0.237±0.15 g respectively. There was significant differences in mean length and weight of females and males (P<0.05). The mean total annual sex ratio of males:females for this species was 0.57 and in this species also sex ratio differed significantly from 1:1 (X2, P<0.05) and skewed towards females in the population of this species. The spawning season of Palaemon elegans extended from May to September with a peak in July . Mean fecundity of this species was 642.7±313.4. The growth coefficients LOO and K for females were estimated as 42.119 mm and 2.40 /Year and 33.87 mm and 2.50 /year for males respectively. The mean. CPUA ( catch/ Km2 ) for this species was 0.75±3.86 kg/km2 and the correspondance biomass was calculated as 382.1 kg in 0-10 m depth .

Lake Nasser fisheries: recommendations for management, including monitoring and stock assessment

This study sought to improve the baseline knowledge of the fisheries of Lake Nasser and to make recommendations for the improved management of the fisheries, including stock assessment. The study included the review of key literature, visits to fisheries infrastructure and fishing camps, and individual consultations with the key stakeholders by means of semi-structured interviews, as well as a collective stakeholder consultation workshop. A preliminary stock assessment was also undertaken using the most recent time series of catch and effort estimates.

Stock enhancement in Japan and Taiwan

Stock enhancement has been recognized as one of the essential strategies that can sustain and increase the resources of coastal fisheries. It has been practiced for over a century, with more than 100 species released to date in worldwide programs. Among the countries in Asia, Japan and Taiwan have already established the practice of stock enhancement. Details are given of the main species, number or seedstock produced and released in 1996 in Japan. The species released by the Taiwan Fisheries Research Institute 1976-1995 are also described.

Population dynamic and stock assessment of lobster resources of Cha-bahar region (with particular ref. to Panulirus homarus)

Amoungst the three spiny lobster species in southern Iranian waters, Panulirus homarus is the only commercial species with a total landings of 20-45 tons per year indicating a decrease in both landings and CPIJE in recent years. Fishing has been regulated according to the no. of fisherman and effort, and trap ha's replaced the gillnef since 1994. Fishing is carried out along the rocky shores of Chah-Bahar region through different landing places by local fisherman for a period of about two months. Most of catch is exported mainly frozen. This research was sposored by the Fisheries Research Dept. and aimed to work on the population dynamics and stock assessment in order to stablish a better understandings of the stock and hence a proper management in this region. Sampling was done for. 10 successive months in _5 major landing places from 1994 to 1995 with no sampling during the monsoon period through June to July. Althogethere, 8500 specimen were collected and the biometry was done accordings to the sex, region and month. Average total length, total weight and carapace length was obtained 216mm., 452 gr. and 75mm. respectively. Total length-weight relationship of both sexes was calculated and follows the cubic law. Regression coefficients for both sexes was 2.8231, males 2.9616, total females 2.7490, berried females 2.6611- and non-berried females

A study on stock enhancement/restocking of the Kyoga basin lakes

Increased management attention to the fisheries tn Uganda is fuelled by five major factors:socio-economic demands, human population increase,stock depletion, biodiversity loss and,environmental degradation.Fish exports from Uganda to overseas and regional markets have rapidly increased since the mid 1990s and it is estimated that total exports are worth at least US$ 200m three quarters of the value due mostly to Nile perch exports to overseas markets.Exports to regional markets are dominated by variously processed tilapia "mukene" (Rastrineobo/a argentea),Nile perch "angara"(A/estes baremose) and cat fishes.Virtually all major water bodies contribute to this trade. A combinatilm of exports and an increased human population has seen the per capita fish consumption in Uganda drop from 15kg in the early 1990s to almost 10kg by 2005.this figure is below the WHO recommended fish protein intake of 17kg. the apparent fish gap in a liberalised economic framework has stimulated interest in commercial fish farming

Approaches to the evaluation and management of the fish stock in Kainji Lake, Nigeria

Estimates of potential yield for Kainji Lake, and the methods of analysis by earlier workers are discussed. Also summarized is the state of the fishery after impoundment, between 1969 and 1971, based on experimental gillnet catches. Recent sampling of the young of the year along the littoral margin indicates that most of the commercially important species have spawned successful1y in the lake. An intense fishing mortality of juvenile fish, owing to the use of small mesh nets by local fishermen, presents a possible threat to the future establishment of the fish in the lake. The results of gill-net selection studies based on HOLT'S (1957) method are given. The data have been extracted from experimental gill-net catches with graded fleets of nets between 1969 and 1971. Recommendations based on the above studies have been made to ensure a successful establishment of the fish species in the lake and an increase in catch-per~unit effort in subsequent years.

Possible fish stock size assessment and available production survey as developed on Lake Kariba

This paper is an outline of methods practically useful for the evaluation of ichthyomass, fish abundance, available production and yield in lakes and rivers. Terms and concepts are reviewed, and difficulties stemming from the use of "predetermined" mathematical models are discussed. Sampling with toxicants in blocked-off areas was found to be the most practical method and is described in detail. For the total estimation of ichthyomass the spatial ranges of fish distribution must be determined; the results of echo-sounding surveys for horizontal, vertical, topographical, seasonal and diel fish distribution are given. Some of the most important methods for computing available production are listed and applied to Lake Kariba as an example. In particular, a method based on the balance between the main predator and prey species is reviewed. The ecological production survey concept is finally stressed as applied to multispecies fish stocks.