Developing a growth-transition matrix for the stock assessment of the green sea urchin (Strongylocentrotus droebachiensis) off Maine

The green sea urchin (Strongylocentrotus droebachiensis) is important to the economy of Maine. It is the state’s fourth largest fishery by value. The fishery has experienced a continuous decline in landings since 1992 because of decreasing stock abundance. Because determining the age of sea urchins is often difficult, a formal stock assessment demands the development of a size-structured population dynamic model. One of the most important components in a size-structured model is a growth-transition matrix. We developed an approach for estimating the growth-transition matrix using von Bertalanffy growth parameters estimated in previous studies of the green sea urchin off Maine. This approach explicitly considers size-specific variations associated with yearly growth increments for these urchins. The proposed growth-transition matrix can be updated readily with new information on growth, which is important because changes in stock abundance and the ecosystem will likely result in changes in sea urchin key life history parameters including growth. This growth-transition matrix can be readily incorporated into the size-structured stock assessment model that has been developed for assessing the green sea urchin stock off Maine.

Morphometry and population dynamics of Sepia aculeata, (Orbigny - 1848) along the Bombay coast

Cephalopods gained importance in the fishing industry when they emerged as one of the leading sea food products exclusively for international market in the mid seventies. Cephalopods fishery in India is still in an infant stage with vast scope for exploitation. The present work on the cephalopods fishery along the Bombay coast is an effort to quantify the resource potential of Sepia acculeata. The morphometry, growth parameters, mortality (total, natural and fishing) rates, the yield per recruit and standing stock were studied.

Feeding trials of green seaweed Ulva fasciata

For the nutritional evaluation of green seaweed Ulva fasciata, a feeding trial was performed in albino rats. The results indicated that the 20% replacement of seaweed U. fasciata instead of carrot or lettuce in rad diet causes no harmful effects, as evident by a non-significant change in blood constituents and serum enzyme levels. The weight gain observed in rats with U. fasciata diet was same as that of control diet. The true digestibility ratio of U. fasciata was 80.20% with carrot and 83.4% with lettuce. The data suggest that the green seaweed U. fasciata could be used as an alternative dietary component in animal fodder.

Bacterial quality and depuration of the green mussel Perna viridis from natural beds

Green mussel (Perna viridis) and sea water from their natural beds on the coastal areas of Porto Novo were studied between April and August 1996 for their bacterial quality. Water samples from the beds were also analysed for their physico-chemical parameters. The total bacterial count of mussels from natural beds as well as bed waters ranged 10³ organisms per gram of mussel meat suspension and per milliliter of sea water. The faecal coliforms were found to be within the permissible limits. Pathogenic bacteria such as Salmonella spp., Streptococcus spp. and Staphylococcus spp. were absent. The variations in pH, temperature, salinity and dissolved oxygen of the seawater samples were insignificant. The mussels were subjected to depuration by different methods among which chlorination was found to be most effective.

Systematic study of the blue green algae of Ceylon kept at the herbarium of the Royal Botanical Gardens, Peradeniya

The collection of blue green algae kept at the herbarium of the Royal Botanical Gardens, Peradeniya, was collected by Ferguson more than 70 years ago. Since then many changes have taken place in the taxonomy of the blue green algae. West (1902), Lemmermann (1907), Wine (1915), Crow (1923), Bharadwaja (1934) and Holsinger (1935) had described some of the blue green algae of Ceylon. While examining the collections of blue green algae kept at the herbarium, the authors found that most of the identifications were incorrect and required revision. In the present paper 20 blue green algae are described. The classification and key to the species are based on the characters given by Desikachary (1959). Blue green algae are important to fisheries since Chanos larvae feed on them.

Morphometry and length-weight relationship of Coilia dussumieri, Valenciennes, 1848 from Mumbai waters

Coilia dussumieri Valenciennes, 1848 a component of 'dol' net fishery forms an important pelagic resource along northwest coast of India. The present communication deals with morphometry and length-weight relationship of this species along Mumbai coast. Morphometric study showed a positive correlation among the compared characters. The length-weight relationship for the species from Mumbai coast was found to be W=0.017L super(2.4223).

Morphometry, length-weight relationship and biology of Sepia aculeata (d'Orbigny, 1848) from Mumbai coast, India

Seventeen morphometric characters of Sepia aculeata of Mumbai coast have been studied and the relationships of morphometric characters with dorsal mantle length (DML) were established. The characters compared showed a fair to high degree of correlation ('r' 0.63-0.99). Number of arm suckers and shell rings were related with DML. The shell rings also showed high degree of correlation with DML ('r' 0.79-0.95). However, the relationship between arm suckers and DML was not so good ('r' 0.1-0.4). The length-weight relationship is described as W=0.1821336 L sub(2.801102). Food and feeding analysis confirm the carnivorous feeding behaviour of the species. Mature females found in all months indicate that it has prolonged spawning season with two peaks, september and march-april. Absolute fecundity ranged from 214 to 4143 eggs.