S M Shivaprakash’s scientific contributions

Physico-chemical parameters of Nethravathi-Gurupur estuary of Mangalore Coast, Karnataka, India Narasimhaiah N.1, Rajashekhar K.P.2., Shivaprakash S.M.3 and Yambem Tenjing S.4 1,2Department of Applied Zoology, Mangalore University, Mangalore, Karnataka, India 3Department of Fisheries Resource Management, College of Fisheries, Mangalore, Karnataka, India 4Sagolband Meino Leirak, Imphal, Manipur, India Corresponding author: nsimhaaz.03@gmail.com, Mobile: 6364400105 Nethravathi-Gurupur estuary is produced by the merger of the rivers Nethravathi and Gurupur which merges into the Arabian Sea near Mangalore, Karnataka. In the present study, seasonal fluctuations were noticed for the majority of the Physico-chemical parameters studied during July 2009-June, 2011 at Site 1, 2, and 3 in the Nethravathi-Gurupur estuary. Southwest monsoon rainfall and municipal discharge play an important role in altering the physicochemical parameters of the estuarine waters. The temperature and salinity values were lower during monsoon than during pre-and post-monsoon seasons. The dissolved oxygen and pH concentrations were observed to be uniform throughout the estuarine waters with minimum seasonal variations.

Background: Gerrids under family Gerridae are important in contributing rich source of protein. Gerres species are economically important food in India. They take a good role in development and economic of Indian estuaries. In fish biology, knowledge of the length-weight data and condition factor (Kn) is an important tool. Gerres filamentosus is one of the economically important groups of fishes inhabiting Karnataka coast. It was selected as a candidate for the present study since the knowledge on length-weight data and condition factor will be helpful in mass culture and production of this species in Karnataka. Methods: The length-weight relationships and condition factor of 2020 specimens of fish, G. filamentosus from Mangalore, Karnataka, south west coast of India, were studied from July 2009 to June 2011. The length-weight relationship was found using parabolic equation. Analysis of co-variance was used to test the significant difference in estimates of “b” between sexes. The condition factor for individual fish was calculated using the formula Kn = Wo/Wc. Result: The relation between the total length (L) and total weight (TW) was described as LogTW = -1.7716 + 2.9511 Log L for females, Log TW = -1.7526 + 2.9364 LogL for males and LogTW = -1.8343 + 2.9720 LogL for indeterminate fishes. The highest and lowest condition factor (Kn) values in females was in December 2010 (1.1186) and September 2010 (0.8871), respectively. Similarly, the highest and lowest Kn values in male was in March 2011 (1.0630) and September 2010 (0.6977), respectively. The result of length-weight relationships could be used for fishery to approve appropriate regulations for sustainable fishery management. The present findings could also be useful for ecosystem modeling. In the present study, changes in Kn value may be in relation to some other reasons than reproductive cycle and feeding intensity.

Uroteuthis (Photololigo) duvaucelii is one of the commercially important inshore squid resources off the south-west coast of India. Length-weight relationship for this species indicated no significant difference between the sexes and hence, the relationship for both the sexes was represented with the common equation W = 0.4624 L2.1158. U. (P.) duvaucelii spawned throughout the year with peak spawning in May. Absolute fecundity ranged from 1,545 to 13,585 eggs with an average of 7,554 eggs. Size at first maturity indicated that females matured earlier at 70 mm DML (dorsal mantle length) whereas males matured little later at 90 mm DML. Males were observed to be dominant during most of the study period with overall male to female ratio of 1:0.93. Seasonal and size dependent variations in sex ratio were distinct.

Fisherwomen contribute substantially to the Indian fisheries economy in general and to the Karnataka State marine economy in particular. Fisherwomen form a invisible workforce but they are dominant in shore based activities such as processing, vending and trading of fish. Studies have revealed that the fisherwomen's contribution to the family income was found to be vital and indispensable for the fisher families' livelihood. The present study deals on awareness and participation of fisherwomen in beneficiary programmes of State Fishery Department, which are especially for the benefit of fisherwomen. The study was conducted in three selected villages of Dakshina Kannada district of Karnataka State using multi stage random sampling method. From the findings, it was observed that, Nearly 67 per cent of the respondents had a medium level of awareness on beneficiary programmes of State Fisheries Department, and 50 per cent of that respondents had a low level of participation in those beneficiary programmes. The study also revealed the constraints faced by the women who involved in fish marketing. Major constraints faced by the women fish retailers were high interest rate charged by money lenders, no proper allotment of space for fish retailers in market place, lack of cooperation on the part of fishery officials and long working hours were yet other major constraints faced by the women fish retailers. Despite of this attempts have been made to overcome the existed constraints.

A field survey was conducted to document the Indigenous Technical Knowledge (ITK) of fisherfolk of Karnataka. Profile analysis of the respondents showed that majority were of old age (above 45 years), had primary level of education, were married and had a minimum fishing experience of 20 years. Majority had a family size of more than 4 members and nuclear families and dwelled in pucca houses. The Indigenous Technical Knowledge of the fisherfolk of fishing villages, Bengre, Dumavathi,Ullal and Kulai belonging to Dakshina Kannada district were collected and the scientific rationale for the same was studied.

The monthly percentage contribution of mackerel catch to the total catch varied from 0.42% (May) to 15.01% (August). Fishers' perception on responsible fisheries and their awareness on responsible fisheries were assessed in the field. It was observed, that they were aware of Code of Conduct for Responsible Fisheries (56%). However, it was observed that 44 percent of the fishers were not aware of importance of basics of CCRF. All the fishers were aware of the reason for ban. According to fishers, some of the reasons for ban were safety measures (86%), breeding season of fish (62%) and also to reduce the fishing pressure (60%). Out of 4 fishing villages 77% of fishers agreed that catch increased immediately after the ban period, said that many technical measures aimed at the conservation and recovery of fish stocks are based on the implementation of minimum mesh sizes to guarantee a certain level of fishing gear selectivity. The gear selectivity is one of the important tools in responsible fisheries. It is very important method to avoid by-catch and to protect juveniles. So there is proper identification of mesh size for all fishes required.

Studies on breeding periodicity of Liza macrolepis inhabiting Mangalore waters indicated that this species spawns only once in a year over a period extending from June to November with a peak during July to August. Data on the size at first maturity of Liza macrolepis using cumulative frequency method showed that male attained first maturity at 223.64 mm T.L., while the female at 236.36 mm T.L. Male always recorded lower Gonado-Somatic Index (GSI) values than female due to higher ovary weight compared to testis. The GSI values were high during June to November with peaks in July and August indicating the spawning period of this fish. The fecundity of fish ranged from 1, 22,278 to 6, 74,232 eggs, with an average of 2, 84,146 eggs. Log linear relationships were established between fecundity and total length, fecundity and body weight of the fish as well as fecundity and gonad weight. The sex-ratio of male to female was 1:0.85. There was an overall male dominance in the population.

The length-weightr relationship of Rastrelliger kanagurta (Cuvier) was estimated and given by the equations, male W = 0.0052 L 3.1737 and female W = 0.0039 L 3.2686 . The b value did not show significant difference between sexes. Hence, the pooled equation for male and female obtained at W = 0.0045 L 3.2234 . The fluctuation in the relative condi-tion factor (K n) values with respect to size indicated that condition of fish showed that an increase trend in size of fish. The K n value steadily increased up to 21 cm and thereafter decreased and again showed that increasing trend. The seasonal fluctuation in the relative factor of the both the sexes was attributed to the sexual cycle and food intake.

The studies on the length-weight relationship are very important for proper exploitation and management of the population of fish species. In the present study length weight relationship of Rastrelliger kanagurta, was calculated as W = 0.03741 L2.7829 for male; W = 0.0744 L2.5724 for female and W= 0.00599 L 2.6777 for pooled fishes. The monthly mean relative condition factor (Kn) values obtained during the present study varied between 0.9934 (in the month of June) to 1.0104 (in the month of May) for males and 0.9955 (in the month of June) to 1.0157 (in the month of May) for females, with an average value of 1.0043 for males and 1.0065 for females, indicating slightly good condition of the fish. In the present study, there was found that there is not significant at 5% level in male and female fish.

To know the breeding seasonality of Indian mackerel, Rastrelliger kanagurta off Mangalore coast the present investigation was undertaken. The present study is based on the observation of a total of 371 Rastrelliger kanagurta individuals ranging in size from 15 to 26 cm. Monthly samples collected from Mangalore Main fish landing centre from March 2009 to February 2010. In fecundity study, maximum size of ova measured up to 0.68 mm. In stage VI(a) and in stage VI(b) mode of advanced group get sifted to 0.73mm from previous stage at 0.65mm was a mode at.0.65mm. Maximum size of the ova being 0.76 mm, it is clear that the size at first maturity for male appears to lie between 19 and 21 cm with an average length 20 cm. In case of female, all were in immature stage up to 15-17cm. The fecundity in Rastrelliger kanagurta ranged from 84,896 to 94,794 eggs with an average of 90,819 eggs.