NISCAIR Online Periodicals Repository Collection: IJMS Vol.32(3) [September 2003]

Sea mammals in marine protected area in the Gulf of Kachchh, Gujarat State, India

Fri, 29 Aug 2003 22:58:59 GMT

Title: Sea mammals in marine protected area in the Gulf of Kachchh, Gujarat State, India

Authors: Singh, H. S.

Abstract: Marine National Park and Sanctuary (collectively designated as Marine Protected Area or MPA) in the Gulf of Kachchh in Gujarat State has coral reefs, mangroves, sea-grass beds, mudflats, network of creeks and other ecosystems which supports rich marine life, including sea mammals. Although a total of 13 sea mammals have been recorded, only small mammals like dolphins, porpoise and dugong visit shallow water areas of the MPA during high tides to collect food. In this study, three marine mammals-common dolphin (Delphinus delphinus), porpoise (Neophocaena phocaenoides) and dugong (Dugon dugon) were counted. Common dolphin has relatively good population in the western part of the MPA but other two species-porpoise and dugong are very rare. The study reveals that about one third of the total area of the MPA in this zone support about 80% of the marine mammals which visit the area during high-tides. Unlike central and eastern zones, the western zone is relatively free from developmental activities like ports, jetties, petroleum industries and other human activities. Thus, this part of the MPA is key habitat for dwindling population of the marine mammals.

Page(s): 258-262

Estimating dolphins weight: Some evidence of seasonality

Fri, 29 Aug 2003 22:58:59 GMT

Title: Estimating dolphins weight: Some evidence of seasonality

Authors: Kumar, Kuldeep

Abstract: A model for estimating the weight of dolphins is proposed by comparing the weights of dolphin kept in captivity with those in the wild. Consistent with the hypothesis, seasonality in dolphins weight was observed. Seasonal indices are obtained which reveal, average the weight of the dolphin varies in different months over a period of year.

Page(s): 255-257

Length-weight relationship and relative condition of a silver biddy Gerres oblongus (Pisces: Perciformes) from the Jaffna lagoon, Sri Lanka

Fri, 29 Aug 2003 22:58:59 GMT

Title: Length-weight relationship and relative condition of a silver biddy Gerres oblongus (Pisces: Perciformes) from the Jaffna lagoon, Sri Lanka

Authors: Sivashanthini, K.; Abeyrami, B.

Abstract: Cultivation of Gerres oblongus is likely to be profitable because of the consumer demand. The values obtained for the mean weight by sex show that females were significantly (P<0.05) larger than males. Covariance analysis for length–weight relationships of male and female fishes reveals that there was significant variation between male and female fishes (P<0.05). The calculated length-weight relationships of W=0.01127xL^2.958 and W=0.015319xL ^3.126, obtained for males and females respectively. The exponent value, b=2.958 for males and b=3.126 for females, not significant from 3 (P>0.05) reflect an almost isometric growth in both instances. The relative condition of fish showed seasonal variation. The highest median values of average condition factor recorded from 175 to 225 mm total length clearly shows that G. oblongus would be in good condition if harvested at this total length range. Males, generally are in better condition than females. The low relative condition values in February to June indicate female G. oblongus spawn during February to June during which the breeding stock should be protected in order to maintain the sustainable exploitation of this species.

Page(s): 252-254

Diel feeding periodicity, gastric emptying, and estimated daily food consumption of whelk (Rapana venosa) in the south eastern Black Sea (Turkey) marine ecosystem

Fri, 29 Aug 2003 22:58:59 GMT

Title: Diel feeding periodicity, gastric emptying, and estimated daily food consumption of whelk (Rapana venosa) in the south eastern Black Sea (Turkey) marine ecosystem

Authors: Seyhan, Kadir; Mazlum, Evren R.; Emiral, Hacer; Engin, Semih; Demirhan, Sefa

Abstract: Gastric emptying, food consumption and feeding periodicity of Rapana venosa were investigated under laboratory conditions and in the field respectively. Gastric emptying was best described by an exponential function, that was independent of meal size and the range of animal size when rapana were fed on fresh mussel. The fresh mussel (0.92-2.19 g) was fully digested by an average of 47 g rapana within the 6-8 hours. No change in feeding intensity was detected over 24 hours suggesting that rapana feed continioussly. Using gastric emptying rates from the laboratory studies, the data obtained from the field was converted to the food consumption estimates and concluded that an average of 50 g rapana in the eastern Black Sea marine ecossystem consume 0.17-0.30 g. mussel in a day, meaning that rapana in the eastern Black Sea marine ecosystem may cause an important predatory impact on the mussel beds.

Page(s): 249-251