Sujitha Thomas

Investigations on unexplored brachyurans (Decapoda), Charybdis hoplites (Wood-Mason, 1877) and Charybdis smithii MacLeay, 1838, from trawl discards of the Southeast Arabian Sea ecosystem

The effectiveness of GIS-based resource mapping to strengthen the database for Ecosystem-Based Fisheries Management (EBFM), was tested in an attempt at resolving the existing gap in the data on non-commercial resources. In this paper we describe the result of that try by giving an example of one of the most important influential species in the benthic ecosystem of the Southeast Arabian Sea (SEAS). An estimated 2803 t of Charybdis hoplites, a relatively little known species from the coast, are yearly caught and discarded by trawlers operating from the Mangalore fisheries harbour. A GIS-aided study on distribution and abundance estimated, that the average biomass of the species is 322.7 t, at any time in the area covered. This study brings out the fact that a number of non-commercial biota are serving as non-detectable factors in sustaining productivity. The identification of their role and the quantification of their biomass thus constitute important data for an effective implementation of EBFM.

Efficacy of spatial study on catch and effort from fishing vessels for strengthening fisheries management

Ever since marine fishery operations were extended beyond territorial waters of respective states, the need was felt for incorporating spatial component of fishing effort and catch for formulating marine fishery policies. The present study is an attempt of spatio-temporal analysis of changing scenario of fishing operations in GIS platform with catch and effort data collected from fishermen, to highlight the need for the change in approach in fisheries management and also for updating the information of fishing along the Indian coast. Marine fishing operations by commercial fishing vessels operated from different states has extended up to 200 m depth since 2000 and duration of fishing, especially trawling extended from single day to 8-13 days per voyage. Present findings were drawn from the analysis of 1,217 days of trawling operations during 2007-2013 by a sampling trawler supplemented by additional fishing operational data support from a group of commercial trawlers. Study reveals that there is an organised and confidential maintenance of log sheets in most of the progressive trawler operators and the information available in spatial platform can be utilized for better fisheries management with fishermen’s participation. Spatial analysis of fish catch from the sampling trawler operated from Mangalore showed that more than 70% of the fish landed in Mangalore was brought from the area beyond the territorial waters of Karnataka signifying that majority of fish catch landing to the state is from waters beyond their jurisdiction. Even though the fishery beyond territorial waters of all maritime states is s governed by Government of India, so far, there is no comprehensive management plans regarding fishing operations beyond territorial waters of the states. The study further reveals that fishing grounds beyond territorial waters of each state are being intensively fished without any fishing regulations and there were many conflicts being reported from these waters concerning the fishing rights of different sectors and different states. In the light of the findings from the study on fishing operations and fishery, an action plan to regulate the fishery off the territorial waters of each state is felt essential. “Regional fisheries committees” with members constituting the officials from neighbouring states sharing same resources with the aegis of Central Government is recommended as a viable option to take care of the management of the fishery within the Indian EEZ.

Food and feeding habits of the narrow barred Spanish mackerel Scomberomorus commerson (Lacepede, 1800) off Karnataka,south-west coast of India

Scomberomorus commerson were collected on weekly basis during January 2012 to December 2014 at Mangalore Fishing Harbour. Stomach of 214 narrow barred Spanish mackerel measuring from 48 to 105 cm fork length (FL) for males and 45.5 to 115 cm FL for females were analysed to study their feeding habits. Fish with empty stomach were prevalent in almost all the months. Prey mainly comprised of fishes and crustaceans, with the fish component forming 99.9%. The index of relative importance (IRI) showed that the dominant prey were semi-digested fish remains (44.6%) of Sardinella longiceps (30.1%), Decapterus sp. (18.7%), whitebaits (2.5%), Rastrelliger kanagurta (1.5%) and Epinephelus spp. (1.1%), while Saurida sp. (0.7%), Megalaspis cordyla (0.5%), Scombroides sp. (0.2%) and shrimps (0.1%) were found occasionally in the gut. Index of stomach fullness (SFI) was 0.11 in August and 0.65 in January. Generally, SFI was higher during September to January and lower during February to August. The empty stomach ratio (ESR) ranged from 33.3% (August) to 92.3% (April).