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Ravikumar, T.; Neethirajan, N.; Chandran, S.; Sangaralingam, M.; Natarajan, J.; Umamaheswar, T., and Padmavathy, P., 2024. Ichthyofaunal diversity from longline catches in the Gulf of Mannar (GoM), southeast coast of India. Journal of Coastal Research, 40(1), 115–128. Charlotte (North Carolina), ISSN 0749-0208. The present study aimed to document the spatial and temporal ichthyofaunal diversity of reef associated fishes caught with experimental longlines fitted with different "J" hook sizes (no. 12, no. 9, and no. 6) and shapes (Straight, Kirbed, and Reversed) from the Therespuram and Mundhal fish landing centres of Gulf of Mannar (GoM), Southeast Coast of India. Sampling was done at a fortnightly interval from February 2020 to January 2022. The total of 21,322 fish diversity includes 37 species of fish belonging to 15 genera, 10 families, and seven orders have been recorded during the study period. Order wise and species wise landing revealed the dominance of Perciformes with five families (Haemulidae, Lethrinidae, Lutjanidae, Nemipteridae, and Serranidae) and 28 species while in the case of order Centrarchiformes it represented with only one species. Fish diversity of GoM was assessed by calculating the various diversity indices such as Shannon–Weiner biodiversity index (H′) ranged from 2.31 to 3.29, Simpson's Dominance Index (1-λ′) ranged from 1.80 to 4.73, Pielou's Species Evenness index (J′) ranged from 0.90 to 0.99, and Margalef index (d) of species richness ranged from 2.03 to 4.73. The results of the present study revealed that the experimental longlines caught one endangered (3%), four vulnerable (11%), two not evaluated (5%), one data deficient (3%), and 29 species (78%) of least concern as per the International Union for Conservation of Nature status. The assessment is a prerequisite for understanding the biodiversity and to help fishery managers to evolve new strategies for the sustainable exploitation and conservation of coral reef associated fishes in this region. [ABSTRACT FROM AUTHOR]

Manjunathan, M.; Ravikumar, T.; Chandran, S.; Neethiselvan, N.; Jawahar, P.; Arisekar, U., and Karthy, A., 2023. Catch efficiency and economic analysis for traditional fishing gear (troll lines) operated along the Coromandel and Gulf of Mannar coasts (southeast India). Journal of Coastal Research, 39(6), 1137–1145. Charlotte (North Carolina), ISSN 0749-0208. This study evaluated the effects of three different J hook types, single hook no. 6, double hook no. 6, and triple hook no. 8, on catch rate, catch composition, and economics of two traditional troll-line methods used along the southeast coast of India. Traditionally, the hand- and leg-held troll line has been used in the Gulf of Mannar (GoM), and the outrigger boom-held method has been used on the Coromandel (CoM) coast. The studies were conducted at fortnightly intervals between June 2020 and January 2021. The overall catch rate (no. h21) was found to be highest with the double hook (0.6 fish h21) and lowest with the triple hook (0.04 fish h21) on the CoM coast, while the single hook (0.34 fish h21) and triple hook (0.02 fish h21) showed the highest and lowest catch efficiency along the GoM coast, respectively. The catch composition was constituted by Scomberomorus commerson (36%), Auxis thazard (18%), Euthynnus affinis (16%), Caranx ignobilis (13%), Thunnus albacares (9%), Scomberomorus guttatus (7%), Coryphaena hippurus (0.8%), and Istiophorus platypterus (0.2%) in the GoM, while it was Thunnus albacares (45%), Euthynnus affinis (18%), Auxis thazard (14%), Istiophorus platypterus (7%), Coryphaena hippurus (6%), Acanthocybium solandri (5%), Scomberomorus commerson (3%), and Caranx ignobilis (2%) on the CoM coast. The chi-square test showed a significant correlation between hook type and fish composition (χ2 = 9650.6, df = 16, p < 0.05). The current study demonstrated a net profit improvement of 3313 rupees/trip at GoM and 2093 rupees/trip at CoM. The benefit-cost ratio (B:C) for GoM and CoM was calculated to be 1.84 and 1.76, respectively. [ABSTRACT FROM AUTHOR]

The length‐weight relationships were estimated for three reef fish species caught in the Gulf of Mannar, India using experimental longlines. The longline fishing took place from December, 2019 to September, 2021 in fortnightly intervals, using longlines (2400 m, 2700 m and 3360 m each), equipped with each 600 various "J" type fishing hooks (straight, reversed, kirbed). The hook sizes used were standard size numbers 6, 9, and 12. The longlines fabricated with polyamide monofilament line were operated from 20 to 50 m depth for 3–5 hours each time. Overall, 81,000 hooks were deployed in 45 fishing trials. The total length and total weight of the combined sex group was recorded nearest to 0.1 cm and 0.01 g, respectively. By using the logarithmic transformed data, linear regression analysis was performed to calculate a and b values for three fish species to establish length‐weight relationships. The parameters for the length‐weight equations for three species are provided along with respective coefficient of correlation and the 95% confidence intervals. A new maximum total length was recorded for two grouper species, viz., Epinephelus faveatus (36.5 cm) and Cephalopholis urodeta (46.0 cm). [ABSTRACT FROM AUTHOR]

Length–weight relationships (LWRs) of six finfish species under two families of the order Perciformes collected from Pulicat lagoon (India) are presented in this study. The fish specimens were collected weekly from the catches of shore seine net (with a mesh size of 50mm at the main webbing and 10 mm at the cod end) operated in the lagoon at an average depth of 2.5 m by the local fishermen during the period from July 2018 to April 2019. This study reports the LWRs for five gobiid and one siganid fish species which have no earlier reports on LWRs. The calculated 'b' value ranged from 3.538 (Favonigobius reichei) to 2.677 (Oxyurichthys microlepis) and 'a' value varied from 0.0041 (Favonigobius reichei) to 0.0199 (Acentrogobius cyanomos). This study also reports the new maximum total length (TLmax) for the gobiid fish species Oxyurichthys microlepis. [ABSTRACT FROM AUTHOR]