Problems in culturing black tiger shrimp (Penaeus monodon) the semi-intensive way: an Indian experience

This paper details some of the problems encountered in culturing black tiger shrimp (Penaeus monodon) the semi-intensive way in India, which include aquatic macrophytes; invasions by molluscs, jellyfish and frogs; predators; fouling organisms; and others.

High level of hybridisation in three species of Indian major carps

Thirty individuals of each species of Indian major carps, i.e., Catla catla, Cirrhinus cirrhosus (C. mrigala) and Labeo rohita, obtained from a nursery near Mymensingh, Bangladesh were analysed by means of allozyme electrophoresis. Twenty-one loci were studied. Several loci revealed significant deviation from Hardy-Weinberg expectations caused by deficiency of heterozygotes, indicating Wahlund effects due to problems with species identification. Moreover, bimodal distributions of individual heterozygosity within the three putative species indicated hybridisation. This was confirmed using analysis of individual admixture proportions, as individuals misidentified to species and hybrids between species were observed. Furthermore, factorial correspondence analysis to visualize genetic relationships among individuals revealed three distinct groups containing misclassified individuals, along with some intermediate individuals interpreted as hybrids. Ten per cent of all C. catla and L. rohita had been erroneously identified to species, and 40 per cent of all presumptive C. catla were hybrids between C. catla x C. cirrhosus and C. catla x L. rohita. In the case of C. cirrhosus, 37 per cent of the samples were C. cirrhosus x L. rohita hybrids. Thirty per cent of all presumptive L. rohita turned out to be hybrids between L. rohita x C. catla and L. rohita x C. cirrhosus. The high incidence of hybrids in C. catla might be responsible for slower growth of the fish in aquaculture.

The Commercial, Subsistence, and Recreational Fisheries of American Samoa

Domestic fisheries in American Samoa landed 587,000 lb of fish and invertebrates in 1991 worth $993,000. Most of the catch (78%) and value (80%) was taken by the shoreline subsistence fishery that occurs on the coral reefs surrounding the islands. Artisanal fisheries for offshore pelagic fishes (primarily skipjack tuna, Katsuwonus pelamis; and yellowfin tuna, Thunnus albacares) and bottomfishes (snappers, emperors, groupers) accounted for 16% and 3%, respectively, of the domestic catch. Recreational tournament catches for pelagic fishes represented the remainder (3%). While sportfishing is becoming increasingly important, other domestic fisheries have declined in recent years. The shoreline subsistence fishery has dropped by about 25% over the past decade owing to socioeconomic factors and possibly overexploitation. Artisanal fisheries have also declined precipitously in recent years owing to hurricane-related damages, attrition of fishermen, and competition with imports. Artisanal fisheries show some potential for growth, but may be constrained by marketing issues, vessel capabilities, and limited stock sizes (for bottomfish) or local availability of high-value (pelagic) fishes. In contrast to the small-scale domestic fisheries, American Samoa is also homeport to a distant-water fleet of large purse seiners and longliners that fish beyond the EEZ and deliver about 160,000-220,000 short tons of tuna per year to local canneries.

Population Biology and Life History of the North American Menhadens, Brevoortia spp.

Four recognized species of menhaden, Brevoortia spp., occur in North American marine waters: Atlantic menhaden, B. tyrannus; Gulf menhaden, B. patronus; yellowfin menhaden. B. smithi; and finescale menhaden, B. gunteri. Three of the menhaden species are known to form two hybrid types. Members of the genus range from coastal waters of Veracruz, Mex., to Nova Scotia, Can. Atlantic and Gulf menhaden are extremely abundant within their respective ranges and support extensive purse-seine reduction (to fish meal and oil) fisheries. All menhaden species are estuarine dependent through late larval and juvenile stages. Depending on species and location within the range, spawning may occur within bays and sounds to a substantial distance offshore. Menhaden are considered to be filter-feeding, planktivorous omnivores as juveniles and adults. Menhaden eggs, immature developmental stages, and adults are potential prey for a large and diverse number of predators. North American menhadens, including two hybrids, are hosts for the parasitic isopod, Olencira praegustator, and the parasitic copepod, Lemaeenicus radiatus. Although the data are quite variable, a dome-shaped Ricker function is frequently used to describe the spawner-recruitment relationship for Atlantic and Gulf menhaden. Each of these species is treated as a single stock with respect to exploitation by the purse-seine reduction fishery. Estimates of instantaneous natural (other) mortality rates are O.45 for Atlantic menhaden and 1.1 for Gulf menhaden.

A Review of Indian Ocean Fisheries for Skipjack Tuna, Katsuwonus pelamis, and Yellowfin Tuna, Thunnus albacares

Skipjack tuna, Katsuwonus pelamis, and yellowfin tuna, Thunnus albacares, together comprise the most important component of Indian Ocean tuna catches. Catches of these species by Indian Ocean fisheries have been increasing over the last decade and totaled 262,300 metric tons (t) in 1986 (Fig. 1; Table 1). Skipjack tuna was the most important species at 32 percent of the total tuna catch in 1986; yellowfin tuna was the second most important at 25 percent. Skipjack tuna are found throughout the Indian Ocean from the Gulf of Arabia in the north to lat. 40°S (Fig. 2). Yellowfin tuna are also distributed throughout the ocean to about lat. 50�

Soundings: the Newsletter of the Monterey Bay Chapter of the American Cetacean Society. 2012

Issues January - November/December 2012. (PDF contains 88 pages)