Puffer proliferation in tropical coastal waters: influence of indiscriminate trawling

Intensive mechanized fishing has induced marked alterations in coastal marine ecosystems resulting in proliferation of low-value, nuisance species in marine fish catches. Assessment of 75 shrimp trawl catches taken in the near-shore waters off Goa, west coast of India during active fishing periods from 2006 – 2008 revealed that the demersal pufferfish, Lagocephalus spadiceus constituted ≈ 27 % by weight of the trawl catch during January – March, and its catch was inversely related to prey and predator species. Sub-tidal rock reefs and submerged rocky patches in the study area offer suitable substrates for spawning, and the predominance of adults during these months suggesting spawning migration. Comparison of the present data with published literature indicates a significant reduction in puffer predators (catfishes). Excessive removal of high-value predators favours the proliferation of pufferfish and its establishment as a meso-predator, probably triggering a potential trophic cascade. The paper discusses the role of removal of High Trophic Level (HTL) species in the proliferation of a meso-predator and its impact on ecosystem function

Population biology of some species of crabs along Goa, west coast of India

1742-1749The population biology of brachyuran crab species namely Leptodius exaratus, Epixanthus frontalis, Metopograpsus frontalis and Heteropanope glabra, were examined at monthly interval from March, 2014 to August, 2015 along the five intertidal habitats of Goa. Out of 4068 crab samples, 46 % were males and 54 % females, of which 22 % were ovigerous females. The maximum carapace width (21.6 mm) was observed in E. frontalis and minimum (9.0 mm) in H. glabra. Seasonally, the L. exaratus, M. frontalis and H. glabra were abundant during the pre-monsoon season whereas, E. frontalis was abundant in the post-monsoon season. The sex-ratio revealed that males and females were abundant during monsoon whereas gravid females were found in plenty during both pre-monsoon and post-monsoon seasons. In overall size &ndash; frequency distribution, the males exceeded the females in L. exaratus, M. fontalis and H. glabra. The Chi-square test revealed a significant ratio of male and female, only in L. exaratus and H. glabra. The fecundity index was highest in M. frontalis (3630) and least in H. glabra (648).</em

Seasonal variation of major elements (Ca, Mg) and trace metals (Fe, Cu, Zn, Mn) in cultured mussel <i>Perna viridis</i> L. and seawater in the Dona Paula Bay, Goa

411-415The major elements and trace metals were analysed from nussel tissue and the seawater taken from three depths (0, 5 and 9 meters) from the culture site. Range of variation in Ca, Mg, Fe, Cu, Zn and Mn were 226-399; 708-1329; 0.005-0.084; BDL-0.042; 0.01-0375; BDL-o.0099 ppm in the water medium and 1124-1950; 984-4783; 1862-8261; BDL-39; 133-1766 and 44-179 mu g/g dry wt in the mussel tissue respectively. The major elements displayed seasonal variation with low values during monsoon period in the water. Among trace metals, Zn and Mn seem to follow almost a close relationship in their contents in the mussel tissue and the water. An inverse relationship of Zn, Mn and Cu to some extent was observed with size in the cultured mussels

<span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Chitin degrading bacteria from the prawn <i>Metapenaeus dobsoni </i> M. and their control</span>

77-80<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Studies on isolation and characterisation of chitin degrading bacteria of wild prawns from Goa waters were conducted. Investigations revealed that Vibrios were the major group of bacteria involved. From biochemical tests it was found that the associated bacterial flora were represented by Vibrio angillarum and Vibrio parahaemolyticus. Study on the effect of antibiotics and plant extracts indicated the combination of antibiotics with plant extracts (Ocimum sanctum, Azardirchta indica, Phyllanthus niruri) were found to be more effective indicating the synergestic effect of the plant extract.</span

Food utilization, growth and lactate dehydrogenase activity of the prawn, Metapenaeus dobsoni (Miers) fed with commercial diet

356-360An assessment of commercial diet and its impact on conversion efficiency, growth parameters and an enzyme, lactate dehydrogenase (LDH) activity in the eye was made. The test organisms (Metapenaeus dobsoni) were grown in the laboratory using commercial diet (low protein, high carbohydrate and no lipid). It was observed that the growth rate using this diet was not encouraging and could not transform energy at optimum level resulting into low protein and high carbohydrate levels in the edible tissue of the prawns. LDH activity decreased with the growth of the prawns fed on this diet. Three isozymes of LDH were observed in the eye tissue. No effect of this diet could be noticed on the isozyme patterns, The commercial diet used in the present study showed marked effect on the activity of LDH in the eye but could not influence the isozyme patterns of LDH

Puffer proliferation in tropical coastal waters: influence of indiscriminate trawling

161-169Intensive mechanized fishing has induced marked alterations in coastal marine ecosystems resulting in proliferation of low-value, nuisance species in marine fish catches. Assessment of 75 shrimp trawl catches taken in the near-shore waters off Goa, west coast of India during active fishing periods from 2006 – 2008 revealed that the demersal pufferfish, Lagocephalus spadiceus constituted ≈ 27 % by weight of the trawl catch during January – March, and its catch was inversely related to prey and predator species. Sub-tidal rock reefs and submerged rocky patches in the study area offer suitable substrates for spawning, and the predominance of adults during these months suggesting spawning migration. Comparison of the present data with published literature indicates a significant reduction in puffer predators (catfishes). Excessive removal of highvalue predators favours the proliferation of pufferfish and its establishment as a meso-predator, probably triggering a potential trophic cascade. The paper discusses the role of removal of High Trophic Level (HTL) species in the proliferation of a meso-predator and its impact on ecosystem function

Catch trends of bottom trawl fauna with an emphasis on prawns and stomatopods, off Goa, India

766-775Catch trends of bottom trawl fauna off Goa, India were investigated at fortnightly intervals from February 2006 – May 2008 with the exception of June – October months (monsoon). Inter-comparison of faunal abundance data obtained during February to April months of 2006, 2007 and 2008 indicated that abundance during 2006 and 2008 were significantly higher as compared to 2007. Available fish landing data for the region also corroborated this trend. The dominance of sub-adults among stomatopods during post-monsoon season (November – January), juveniles and sub-adults among prawns during pre monsoon (February – May), indicated recruitment to the fishery. Comparison with 40-year-old published data indicated significant reduction in the overall yield (P = 0.043; α = 0.05). Additionally, yields of 12 out of 15 fish groups across the demersal trophic spectrum decreased significantly (P = 0.031; α = 0.05). However, catches of miscellaneous species increased 17 times, and were dominated by pufferfishes. The profusion of pufferfish is attributed to the perennial breeding habit of these fishes combined with increased removal of potential predators such as sharks and catfishes. Marine Trophic Index (MTI) and Fishing-in-Balance Index (FiB) decreased at rates of 0.017 and 0.016 per decade, respectively, implying that sustained fishing pressure over the next few decades could lead to potential trophic cascade and dominance of resilient opportunistic species such as puffers

Biochemical composition and caloric potential of zooplankton from Bay of Bengal

70-73Proximate composition and variations in protein, lipid, carbohydrate, ash and organic carbon in zooplankton from 42 stations in the Bay of Bengal are reported. Average percentages of moisture, protein, lipid, carbohydrate, ash and carbon were 85.62, 4.95, 1.54, 0.43, 4.4 and 4.16 respectively on wet weight basis. A good correlation of caloric potential with protein and lipid indicated to a certain extent that protein and lipid act as metabolic reserves of the zooplankton in the area of investigation. No significant correlation was observed between caloric potential and organic carbon. Zooplankton did not show as an extensive source for storage of lipid and carbohydrate

Physicochemical Characteristics Of Fishing Grounds Off Mangalore, West-Coast Of India

201-205In the regions off Mukka and Hosbettu, Karnataka coast, salinity attains maximum value of 35.1 x 10-3 in May. Similarly silicate, nitrate and phosphate show high values (27, 0.12 and 1.32 µM respectively) in May. This indicates upwelling of nutrient rich bottom waters. Changes in chl a and nitrate, phosphate and NO3:PO4 ratio suggest nitrate deficiency. Multiple correlation coefficient of temperature and salinity towards oil sardine landing is highly significant (r = 0.9917; P a content