H N Anjanayappa’s scientific contributions

A total of 601 specimens of Gerres filamentosus were collected from the sampling sites and were subjected to gut content analysis. Guts were visually classified according to the fullness of the stomach. Occurrence, gravimetric and volumetric methods were followed to quantify the gut contents. Feeding intensity was assessed using methods such as the Gastro rosomatic index, mean index of feeding intensity, and index of fullness. Sex wise, month and length group-wise fluctuations in the feeding intensity were also studied. It can be seen that the percentage of actively feeding fish was observed to be high during pre-monsoon and monsoon months. Feeding intensity was at its peak during April and July 2019, and the main food was found to be prawn juveniles, polychaete worms and other detritus matter.

The biometric studies are essential for proper species-level identification of fishes. In total 251 numbers of Puntius sophore specimens were collected from nine Indian states and subject to biometric analysis to provide updated identification keys. The P. sophore can be distinguished from its congeners species by presence of a black spot in the caudal peduncle region, another at the root of dorsal fin between 3 rd to 6 th branched ray, diffused golden spot on gill cover, lateral line complete with 22 to 26 scales including 1-2 scales on caudal fin base, ½4-5/1/3½-4 transverse scales from dorsal and ventral fin origin, 8-9 pre-dorsal scales, 10-11 pre-pelvic scales and 12 circumpeduncular scales, III-IV+8 rays in dorsal fin (consisting of two supernumerary and one unbranched ray) and last unbranched ray osseous and smooth; i+13-14 rays in pectoral fin, i+8 rays in ventral fin, iii+ 5 rays in anal fin, and caudal fin bilobed with 10+9 principal rays. The overall standard length of the collected samples varied between 22.71 to 80.37 mm SL with the mean value of 48.16±9.64. The body depth of individuals varied in the range of 30.43-44.53% of SL with a mean 37.64±2.36, which lies under the range 28.90-51.02% of SL and widest range 34.81-44.53% was observed in Bihar population with a mean value 38.51±2.70. Similarly, head length, length of caudal peduncle and depth of caudal peduncle ranged between 25.24-33.55%, 16.61-23.73% and 12.19-18.30% of SL, respectively. Head depth behind the eye orbit, snout length and eye orbit diameter ranged between 60.04-75.98%, 19.34-28.64% and 26.03-38.91% of the head length.

The length-weight relationship of Cociella crocodila was estimated and corresponding equation was W=0.0032 3.2862 3.2498 L for male and W=0.003 L for female. Analysis of covariance showed that there is no significant difference in length-weight relationship between the male and female. Hence, the pooled equation for both sexes was 3.2708 obtained at W=0.0031L. The fluctuation in the relative condition factor (K) value with respect to size indicated n that condition of fish more or less showed an increasing trend with size of fish. The seasonal fluctuations in the relative condition factor of both the sexes could be attributed to the sexual cycle, food intake and environmental factor.

The length-weight relationship of Charybdis lucifera was estimated and corresponding equation was W=0.1112 L3.1716 for male and W=0.1248 L3.2785 for female. Analysis of covariance showed that there is no significant difference in length-weight relationship between the male and female. Hence, the pooled equation for both sexes was obtained at W = 0.118 L3.2144. The carapace width-weight and carapace length-weight relationship of C. lucifera showed that the weight of crab increased as 3.2144 power of the carapace width. The carapace length-weight relationship showed that the weight of crab increased as 2.7844 power of the carapace length. The fluctuation in the relative condition factor (Kn) value with respect to size indicated that condition of Charybdis lucifera more or less showed an increasing trend with increase in size of crab. The seasonal fluctuations in the relative condition factor of both the sexes could be attributed to the sexual cycle, food intake and environmental factors.

The parameters of length-weight relationship of Otolithes ruber were estimated and corresponding 2.6970 2.6884 equation was W=0.0294 L for male and W=0.0316 L for female. Analysis of covariance showed that there is no significant difference in length-weight relationship between the male and female. Hence the pooled equation for both 2.7017 sexes was obtained at W=0.0268L. The fluctuation in the relative condition factor (k) values with respect to size inn dicated that condition of fish showed that an increase trend in size of fish. The k values steadily increased up to about n 190-210 mm and thereafter showed fluctuation. The seasonal fluctuation in the relative condition factor of both the sexes was attributed to the sexual maturity cycle and food intake.

The study deals with nature and composition of food items, feeding habits, and intensity of feeding of Loligo duvauceli from Mangalore coast. This species was foud to mainly feed on shrimp remains (22.42%), copepod (3.27%), crabs (14.19%), squid (18.24%), fish (18.26%), fish eggs (5.15%), sediment matter (2.81%), Semidigested mater (11.14%), molluscans shells (2.56%) and unidentified matter (2.69%). The study indicated that Loligo duvauceli was a carnivorous feeder. In all size groups starting from 3-5cm to 21-23cm food items such as shrimp , squid, fish , crabs, semidigested mater, fish eggs, copepod, molluscan shells, sediment mater were found in different proportions. The feeding intensity was high during April followed by December, February and poor feeding was noticed during January.

The biometric studies are essential for proper species-level identification of fishes. In total 251 numbers of Puntius sophore specimens were collected from nine Indian states and subject to biometric analysis to provide updated identification keys. The P. sophore can be distinguished from its congeners species by presence of a black spot in the caudal peduncle region, another at the root of dorsal fin between 3 rd to 6 th branched ray, diffused golden spot on gill cover, lateral line complete with 22 to 26 scales including 1-2 scales on caudal fin base, ½4-5/1/3½-4 transverse scales from dorsal and ventral fin origin, 8-9 pre-dorsal scales, 10-11 pre-pelvic scales and 12 circumpeduncular scales, III-IV+8 rays in dorsal fin (consisting of two supernumerary and one unbranched ray) and last unbranched ray osseous and smooth; i+13-14 rays in pectoral fin, i+8 rays in ventral fin, iii+ 5 rays in anal fin, and caudal fin bilobed with 10+9 principal rays. The overall standard length of the collected samples varied between 22.71 to 80.37 mm SL with the mean value of 48.16±9.64. The body depth of individuals varied in the range of 30.43-44.53% of SL with a mean 37.64±2.36, which lies under the range 28.90-51.02% of SL and widest range 34.81-44.53% was observed in Bihar population with a mean value 38.51±2.70. Similarly, head length, length of caudal peduncle and depth of caudal peduncle ranged between 25.24-33.55%, 16.61-23.73% and 12.19-18.30% of SL, respectively. Head depth behind the eye orbit, snout length and eye orbit diameter ranged between 60.04-75.98%, 19.34-28.64% and 26.03-38.91% of the head length.

The spadenose shark Scoliodon laticaudus Muller & Henle (1838), one of the smallest tropical Carcharhinid sharks is locally known as "balyar/ neer thate/chaate" in coastal area of Karnataka coast. The study deals with nature and composition of food items, feeding habits, intensity of feeding of S. laticaudus. Analysis of the gut content in both sexes showed that, fish remains and unidentified and semi-digested matter formed the major food items. Lesser sardines, anchovy, Saurida sp, Nemipturus sp., sardine, Priacanthus sp, Terapon sp, croackers, shrimps, Sepia sp, stomatopods, Loligo sp and molluscan remains also occurred in considerable quantity. The contribution of gut content shows approximately 3.6% lesser sardines, 5.08% Anchovies, 3.05% Saurida sp, 3.16% Nemipturus sp, 3.04% Sardine, 2.91% Priacanthus sp, 2.39% Terapon sp, 1.5% crockers, 28.49% fish remains, 4.47% Loligo sp, 2.25% shrimp, 1.39% Sepia sp, 3.23% molluscan remains, 1.80% stomatopods and unidentified and semi-digested matter 33.62% during the period 2015-16. The gut content consists of approximately 3.05% lesser sardines, 4.28 % Anchovies, 3.35 % Saurida sp, 2.51% Nemipturus sp., 5.43% Sardine, 3.45% Priacanthus sp., 2.65 % Terapon sp., 2.07 % croackers, 19.29% Fish remains, 3.19% Loligo sp., 2.95% shrimp, 2.54 % Sepia sp, 3.12 % molluscan remains, 1.27% stomatopods and 40.85% Unidentified and semi-digested matter during 2016-17.

The present study deals with length-weight relationship of Scoliodon laticaudus from Dakshina Kannada and Udupi coast during September 2015 to May 2017. The regression coefficient of female was found to be higher than male. From this observation it may be opnied that female gained more weight with increase in length compared to male. The corresponding equations for both the sexes were derived during September 2015-May 2016 the corresponding equations were; W=0.00986 L 2.7674 for male, W=0.0084 L2.8129 for female and pooled data was obtained at W=0.00914L2.7802. Likewise, during September 2016 to May 2017 the equations obtained for male W= 0.02138 L2.5826, for female W = 0.01972 L2.7249 and pooled value W= 0.02055 L 2.6585. Analysis of the covariance indicated that there is no significant difference in the length-weight relationship between male and female. The data on seasonal variation in condition factor (Kn) of both male and female during both the years of study showed that the values were more or less similar in both the sexes, indicating almost identical metabolic activity in male and female which may be attributed to gonadal development and feeding intensity.