Aspects of taxonomy and life history traits of engraulids in the context of biodiversity conservation and fisheries management

Engraulids are a major small pelagic resource abundant in the tropical and temperate seas of the world. The prominent snout which is characteristic of this family carries a unique organ called the “rostral organ”. They are small, silvery coloured small pelagics with more than 16 genera and 139 species identified worldwide (Nelsen, 1984) of which 4 genera namely, Anchoa (35 species), Anchoviella (15 species), Stolephorus (19 species) and Thryssa (25 species) constitute the majority of species. They form a major fishery resource in the coastal fisheries of the Indian EEZ. In 2013 the dominant group among anchovies contributing to commercial fisheries were the whitebaits with an estimated 69500 t landed, followed by the other anchovies such as Thryssa (42000 t), Coilia (30767 t) and Setipinna (8507 t). Correct identification of fishes, their eggs and larvae are thus crucial in fisheries management

Marine capture fisheries-Pelagic resources and their management

Pelagic resources contribute around 50% of the total marine fish landings in India and the major contributors include the single species group comprising oil sardine (Sardinella longiceps), Indian mackerel (Rastrelliger kanagurta), Bombay duck (Harpadon nehereus) and the Hilsa shad (Tenualosa ilisha). The lesser sardines (Sardinella spp.), Ribbonfish (Trichiurus lepturus, Lepturacanthus savala), anchovies (Stolephorus spp. Thryssa spp.,), carangids (comprising scads, trevallies, pomfrets etc), seerfishes (Scomberomorus spp.) and tunas (coastal and oceanic) are the other major resource

Beverton and Holt’s yield per recruit model

Yield per Recruit (Y/R) is the expected life time yield per fish recruited into the stock at a specified age. The Beverton and Holt’s Yield per Recruit model (1957), is a predictive model that can be used by fishery managers to understand the biological / economical effect of fishing on the stocks and helps them to take suitable measures to ensure sustainable yields from the fishery. In the Beverton and Holt (1957) yield equation, the response of a population to fishing mortality on a per-recruit basis depends on natural mortality (M), fishing mortality (F),growth rate (K, from the von Bertalanffy growth equation) and the age (tc) at first capture (depends on gear selectivity). A fishery manager will aim at arriving at a combination of measures that will ensure that the fish stocks are exploited at such a level that there is neither growth nor recruitment overfishing, and predictive models employing the Y/R concept enable these decisions. Maximum yield from a cohort can be realised only by exploiting it at an age or size (optimum age or length) at which the cohort’s biomass reaches its maximum. Thus, ideally fishery managers should be implementing exploitation strategies that do not harvest fish too early (by restricting catches of juvenile fishes) or too late when most of them would die due to “senility” or similar reasons operated through natural mortality

Aspect ratio of marine fishes from India

Fish morphometrics is an important aspect in fish taxonomy and fish biology studies. The aspect ratio (A) of fishes is related to metabolism and food consumption. It is also as an attribute for determining swimming speed that influences escape from predators and resulting survival in the wild. In this study the aspect ratio of 54 species of commonly exploited marine fishes using a manual graph method that can be used for comparisons across species is presented. Unlike digital imaging methods, this procedure does not involve the 'perspective' and 'distortion' errors which means that it can be used even for fishes with large caudal fins and allows results to be compared with other studies

Insights on diet dynamics of Indian mackerel Rastrelliger kanagurta (Cuvier, 1816)

The diet of Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) is reported based on the gut content analysis of specimens collected along the central Kerala coast, India. The study indicated ontogenetic variations in diet with diet breadth being highest in the largest size class of >231 mm total length (TL). Copepods followed by diatoms were the preferred food items. Detritus was an important diet component, especially during the pre-monsoon season and in the larger (>231 mm TL) size groups. The Preponderal Index (Ip) indicated seasonal differences in proportions of the various prey consumed. Spearman Rank Correlation Coefficient indicated similar diet quality during monsoon (June-September) and post-monsoon (October-January) seasons; but significant differences as compared to pre-monsoon season (February-May). Based on the results of the study, Indian mackerel was classified as an opportunistic feeder with a diet component that broadly reflects its seasonal-spatial habitats and local food availabilit

Pelagic fisheries of India - Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

The pelagic fishes live most part of their life in the surface or subsurface waters. This group exhibits rich species diversity and abundance in the Indian EEZ. Though 240 species constitute the pelagic fisheries along the Indian coast, it is only about 60 species belonging to 8 groups support major fisheries (Table1). During the last decade, pelagic finfishes contributed to 46-56% (average: 51%) of the total marine fish production, of which almost 70% was fished from within the 50 m depth zon

Scombroid Fishery of the Indian Ocean - An Overview

In the Indian Ocean, scombroids comprising of tunas, billfishes, seerfishes and mackerels are an invaluable resource and their producer value is estimated to between 2 and 3 billion US dollars annually, besides the vast socio-economic benefits to the fishing nations. Of the three major groups of species, tunas account for the largest share of the total catch and also for the largest increase during the past 10 years. Seerfish catches attained record levels in 1998 while billfish catches have more than doubled since 1992 although the relative contribution of the group is still small. With the introduction of technologically advanced fishing fleets and techniques in the Indian Ocean, the intensity of exploitation of scombroids, especially tunas and billfishes have reached a new peak. An overview of the present status of scombroid fishery of the Indian Ocean is presented below

Field identification of scombroids from Indian seas

Scombroids are a diverse group of pelagic fishes ranging in size from about 30 cm to over 3 m in length. Most of them, especially the tunas and billfishes perform considerable and sometimes even transoceanic migrations. Being highly valued table fishes, they are of significant importance both as a commercial and recreational fisher

भारत की समुद्री प्रग्रहण मात्स्यिकी एक अवलोकन

कृपया पूरा लेखा पढ

भारत मे ट्यूना मात्स्यिकी का विकास

कृपया पूरा लेख पढे