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Growth performance and cost efficiency of tilapia (Oreochromis niloticus) and milkfish (Chanos chanos) fed extruded floating and non-floating feeds reared in net cages in Taal Lake
Get PDFThis study evaluated the growth and cost efficiency of tilapia (Oreochromis niloticus) and milkfish (Chanos chanos) fed three feed types used in cage farming in Taal Lake, Batangas, Philippines to serve as baseline information for cage aquaculture regulations. O. niloticus and C. chanos were reared in net cages fed three feed treatments: extruded floating feed (EFF), slow-sinking feed (SSF), and sinking feed (SF). Growth performance, feed conversion ratio (FCR), yield, and cost efficiency were compared at harvest. Results of the study showed that EFF had significantly higher mean weight gain, absolute growth and specific growth rate, biomass harvest, percentage good size fish, and FCR than SF in both O. niloticus and C. chanos (P0.05). FCR and biomass harvest were significantly higher in EFF than SF in O. niloticus (P0.05). Survival rate was not significantly different among feed types (P>0.05) in both species. Net profit was significantly higher in EFF than the other feed types (P<0.05). At the same volume of fish production in the lake, the use of extruded floating feeds in cages lessened the feed cost by 17.91-29.44% for higher net returns and decreased feeds use by 19.64-30.0%, which could minimize negative impacts on the lake water environment. The results of the study revealed the comparative advantage of floating feeds over slow-sinking feeds and sinking feeds and is therefore recommended as the ideal feed type for cage farming in the lake
Status of Fisheries Resources of Honda Bay (2003-2013)
Get PDFThis paper discusses the status of fisheries resources of Honda Bay from January 2003 to December 2013. The eleven years annual production data shows a fluctuating trend. There was an increase in the annual number of boat landings of all gear from 95,284 in 2003 to 259,383 in 2011. The highest production was recorded in 2010 with 2,761.83 MT and the lowest in 2007 with 1,555.94 MT. Municipal fisheries contribute a large share of production with 86.03% dominated by Leoignathus splendens with 9.58%, while commercial fisheries share 13.97% dominated by Amblygaster irm which shares 38.95%. The seasonality of fishing operation for municipal fisheries is not pronounced as almost all of the different gears surveyed operate year-round, while the trend of production for commercial fishing operation is influenced by southeast monsoon or “habagat” and northeast monsoon or “amihan”. Selar crumenopthalmus and Rastrelliger kanagurta exhibited only one pulse per year while the Siganus canaliculatus and Lethrinus miniatusshowed two pulses per year. Population parameter estimates showed that of the 10 species analyzed 93% have an exploitation ratio above 0.5, which means that a majority of the common species caught were beyond their regenerative capacity
Blue Swimming Crab Stock Assessment in the Western Visayan Sea
Get PDFPortunus pelagicus (Linnaeus, 1758) known as the blue swimming crab, ranks 4th major fishery export of the Philippines. The Visayan Sea is considered as the major crab fishing ground of the country to which 25 out of 53 crab picking stations are located in Region 6. The study was conducted in the year 2011 to 2012 in ten crab fishing municipalities of the Western Visayan Sea conducting catch and effort, reproductive biology, and biological sampling. Results showed that a decreasing CPUE is observed compared in 1995 at 0.34 kg/ panel to 0.19 kg/panel in 2011 and 0.26 kg/panel in 2012, with 17 to 20 gillnet-panels per boat per day. Surplus production models showed that MSY at 13,150 MT and fMSY at 19,473 gillnet-panels of the Fox model is achieved prior to the year 1999. In 2011 and 2012, yield decreases as a setback of increasing fishing effort. Population parameters results showed growth overfishing where the L∞ value obtained at 19.10 cm for this study was lower compared to 19.95 to 21.77 cm in previous studies. Computed E value at 0.68year-1 is higher than the threshold at E = 0.5year-1 and at optimum E10 = 0.56year-1. Recruitment overfishing is also apparent from the size catches of major crab fishing gears to length at first maturity of 11.5 cm. Bottomset gillnet catches premature sizes by 57%, crab pot by 62%, and otter trawl by 95%. Seasonality of crab catching peaks in July and January coincides with the peak spawning in August and January, and recruitment in October and January
Stock Assessment of Small Pelagic Fishes Caught by Ring Net Fishery in the Camotes Sea, Central Visayas, Philippines (2003-2012)
Get PDFAn analysis of the ten-year data on catch, effort, and length frequency of small pelagic caught from ring net fishery in the Camotes Sea was made. Length frequency data were used to estimate growth, mortality (total, natural, and fishing mortalities) and exploitation levels using the FAO-ICLARM Fish Stock Assessment Tools (FISAT) program developed by FAO/ICLARM.
Generally, the sizes of the major species caught from ring net fishery are smaller than the maximum size they can attain and were harvested before reaching maturity lengths. The probability of capture at L50, however, was higher in 2003-2012 than in 1983-1987 assessment.
Analysis of the recruitment pattern in the Camotes Sea reveals a dual recruitment mode per year starting from April to June which conforms to the findings of Jabat and Dalzell (1988) of which bimodal pattern of recruitment was observed for most of the small pelagic species in the catch of the ring net fishery from the Camotes Sea and in the Philippines in general.
Exploitation rate (E=F/Z) estimates of three dominant pelagic species, Decapterus macrosoma (L∞=27.56 and present E=0.71), Selar crumenophthalmus (L∞=30.03 cm and present E=0.68), and Decapterus kurroides (L∞= 41.64 and present E=0.51) revealed they are vulnerable to ring net fishery as exhibited by high E values exceeding the 0.5 threshold. The present exploitation levels suggest growth overfishing of these pelagic species which will eventually lead to unsustainable ring net fishery in the Camotes Sea
Africa: Lake Victoria, lake ties
Get PDFFisherfolk use their social networks to navigate formal and informal rules in accessing the fisheries of Lake Victori
A survey on plankto an investigation on ecology of mudskippers in Hormuzgan coastal areas communities in Bandar Abbas coastal area
Get PDFThe most important habitats of mudskippers are muddy areas in tidal zone of tropical mangrove forests. Mudskippers are related to Oxudercinae subfamily of Gobiid fishes. Three most distributed species of Hormozgan mudskippers were Periophthalmus waltoni, Boleophthalmus dussumieri and Scartelaos tenuis. These fishes can be considered as euryhaline and eurythermal aquatic species, because they can tolerate a wide range of salinity and temperature. A research was done since september 2008 to september 2009 in two important mangrove regions of Hormuzgan (Tyab and Khamir) to determine some ecological characteristics of inhabited mudskipper species. Results showed that nitrate levels are significantly different between tidal lines and seasons (P<0.05). Maximum nitrite concentrations were recorded 53.2 and 92.5 µg/l in Khamir and Tyab respectively. The annual correlation matrix showed that a positive correlation between phosphate concentration and nitrite and silicate (P<0.05). Silicate concentration was very high, because of too low density of diatoms and radiolarians. Some species of diatoms, dinoflagellates, cyanobacteria and larvae of crustacea and echinoderms were observed with different density and diversity. Sediment composition of the studied areas were categorized in three classes (clay, sand and clay - sand). Polychaetes formed dominant group of benthic fauna in Tyab and Khamir areas. High density of capitellid worms was possibly related to some environmntal stress caused by activity of fishing and cargo vessels. It was not observed significant difference between fishes length in two areas (P<0.05); Mean lengths of P. waltoni, B. dussumieri and S. tenuis were calculated 9.85, 14.7 and 11.5 cm respectively. Spawning period of each three species in both areas were obtained from late winter to late spring based on gonadosomatic index values. Male to female sex ratio of P. waltoni, B. dussumieri and S. tenuis were calculated 1:0.45, 1:0.41and 1:0.74 respectively. Absolute fecundity of P. waltoni, B. dussumieri and S. tenuis were estimated 3558 ± 2202, 3952 ± 1030 and 6742 ± 1939 respectively. P. waltoni feeds mainly on fiddler crab, S. tenuis uses crustaceans and gastropods and B. dussumieri has a vegetarian diet
Weather/forecasting: a fishers’ forecaster
Get PDFAction research by the University of Sussex is bringing fishermen and scientists together to track wind, and waves and save lives. Seen from the air, Thiruvananthapuram, the capital city of Kerala state in south India, looks like a magic carpet – a long strip of golden sand separating a vast green canopy of coconut palms and the turquoise shimmer of the Arabian Sea. These sandy shores are home to the largest concentration of artisanal marine fishers in this part of the world – 42 villages spread along a 48-mile coastline. Many of these fishers are poor
An investigation of ontogenic development of mouth and its size in larval and juvenile of Vimba vimba
Get PDFIn this study, mouth morphological development and the importance of size of pellet food at the onset of exogenous feeding, with respect to mouth size from hatching through 60s day after hatching (DAH), were studied in larval and juvenile Vimba bream (Vimba vimba). The samples were randomly taken at 1-8 DAH, then with 2, 5, and 10 days intervals until 60 DAH (being released into the sea). Morphological examinations of mouth were followed using SEM. The lengths of upper and lower jaws as well as the size of mouth gap at 45° and 90° were calculated to estimate the size of pellet food. The larval mouth opened at 1 DAH and filiform papillae, and lips began to form at 2 DAH. The first taste buds developed at 3 DAH. The larval mouth developed a crescent shape at 4 DAH and the structure of papilla became clear. A number of neuromast cells were observed around the mouth at 8 DAH. Finally, it can be concluded that with the onset of exogenous feeding, Vimba vimba larvae is probably able to ingest and digest 110 µm pellet food since 8 DAH. Thus, since 20 DAH until the end of larval rearing period, formulated diets can only be used
Population assessment and yield per recruit of long tail tuna (Thunnus tonggol) in northern of the Persian Gulf and Oman Sea Sea (Iran, Hormozgan Province)
Get PDFThe purpose of this study was to find some important biological aspects of Thunnus tonggol in coastal waters of Hormozgan Province (Persian Gulf and Oman Sea). A total monthly data of 4383 individuals ranging from 25 to 124 cm fork length were collected from April 2015 to March 2016. The data were analyzed with FiSAT II software using the ELEFAN1 package to estimate the population parameters. The length-weight relationship was TW=0.00002 FL^2.87 (R^2 =0.97) showing an isometric growth for T. tonggol. Growth parameters were computed as L∞=129.6 cm, K=0.39 year^-1 and t0=−0.28 with the growth performance index, φ’ of 8.7. The total mortality (Z) was estimated 1.58 year^-1 using catch curve method. The natural (M) and fishing mortality (Fcurr) were obtained 0.49 and 1.09 year^-1, respectively. The exploitation ratio was 0.69. Length at first capture (Lc) was estimated as 60.2 cm fork length. The yield per recruit (Y/R) maximized in maximum fishing mortality rate 0.85 year^-1. The biomass per recruit decreased to 17.2% of unexploited biomass (virgin biomass) at Fcurr. The current fishing mortality exceeds optimum fishing mortality (Fopt) and limit fishing mortality (F limit) as biological reference points. The results indicated that population of T. tonggol is overexploited in the Persian Gulf and Oman Sea and there no further scope for improving the exploitation of this species
Estabelecimento do período de veda da pesca artesanal do camarão penaeideo na Baía de Inhambene
Get PDFAbstract in english: The study to establish the closure season of artisanal penaeid shrimpp fishing in Inhambane Bay, located in the province with the same name in the south of Mozambique, was carried out between June 2013 and May 2014, covering four fishing pre-defined as shrimp londing sits along Bay.
The specimens in total of 100 individuals of each species from each of 2 day sampling period used for this work were
obtained from fishermen using beach seine and it covered the periods of live and dead tide of each month for 12
consecutive months. The main objective of this work was to study the reproductive biology aspects and size structure of Fenneropenaeus indicus, with a view to establishing the period for the closure season to protect the artesanal fishery database juveniles shrimp in the Bay of Inhambane.
Monthly data extracted from the statistical database of small-scale fishing "Pescart" on fisheries statistics over a series of five consecutive years since 2009, have shown that Fenneropenaeus indicus dominated catches with an average of over 65%. At all sampling sites the shrimp lengths variation was not significant, in spite of a very great abundance in Jogo, followed by Nhaduga. Classes with higher frequency range were between 11 and 18 mm. Therefore, it can be hypothesized that juveniles of Fenneropenaeus indicusin the Bay of Inhambane do not remain for a long time in this area. Population structure of the studied species indicated that the amplitude of the variation of the carapace length of the females was between the classes 5 and 29 mm, with molting in classes 10 and 15 mm and with an average value of 15.8 mm while males ranged from 5 to 28 mm with an average value of 15.1 mm.
In conclusion the closure season may be stablished for the entire Inhambane Bay, system from October to February, to
enable juveniles shrimp to enter the fishing ground, to grow and reach the fishing size to produce sustainable amounts of spawning stock.
Abstract in portuguese:O estudo para o estabelecimento do período de veda da pesca artesanal de camarão penaeideo na Baía de Inhambane, província do mesmo nome a sul de Moçambique, foi realizado entre Junho de 2013 e Maio de 2014, abarcando quatro centros de pesca ao longo da Baía, que foram pré-definidos como locais de captura/desembarque de camarão na área de estudo. A obtenção dos espécimens para o trabalho foi feita mediante a aquisição aos pescadores das redes de arrasto para a praia até perfazer um total de 100 indivíduos de cada espécie em cada um dos 2 dias de amostragem, cobrindo períodos de maré viva e morta de cada mês durante 12 meses consecutivos. O objectivo consistiu em estudar aspectos da biologia reprodutiva e estrutura de tamanhos camarão branco (Fenneropenaeus indicus), com vista ao estabelecimento do período de veda para a protecção de juvenis na Baía de Inhambane.
Dados mensais extraídos na base de dados da pesca artesanal “Pescart”, ao longo de uma série de cinco anos consecutivos desde 2009, mostraram que Fenneropenaeus indicus dominou as capturas com uma média de mais de 65%. Em todos os locais de amostragem a variação dos comprimentos não foi significante, apesar de se verificar uma abundância muito grande em Jogo, seguida de Nhaduga. As classes com maior frequência estão compreendidas entre 11 e 18 mm, pelo que se pode colocar a hipótese de que os juvenis de Fenneropenaeus indicus na Baía de Inhambane não permanecem durante muito tempo nesta área. A estrutura da população da espécie estudada mostra, que a amplitude da variação do comprimento de carapaça das fêmeas situa-se entre as classes 5 e 29 mm, com modas nas classes 10 e 15 mm e com um valor médio de 15,8 mm enquanto que os machos variam de 5 a 28 mm com um valor médio de 15,1 mm.
O período de veda poderá ser definido para toda a Baía de Inhambane a ser implementada a partir do mês de Outubro a
Fevereiro, para possibilitar que camarão pequeno que dá entrada nesta área de pesca possa crescer e atingir tamanho
maior e produzir quantidades sustentáveis de stock desovante