Length-Girth Relationships of Selected Trawl Resources of Cochin Coast, Kerala
Length-Girth Relationships of Selected Trawl Resources of Cochin Coast, Kerala
Date
2020
Authors
Naseeba, P. A.
Madhu, V. R.
Kumar, B. Manoj
Edwin, Leela
Journal Title
Journal ISSN
Volume Title
Publisher
Society of Fisheries Technologists (India)
Abstract
Trawling is a major fishing method which contributes
significantly to the marine catches of India.
Among the many negative impacts that are attributed
to trawling, generation of bycatch is the most
significant and different technical measures have
been adopted world over to reduce bycatch during
trawling operations. The optimum mesh size for a
technical device is determined by conducting
selectivity experiments using different methods, in
which length is the main criteria for analysis.
However, fish retention in the codend is primarily
decided by the girth rather than length, which is
often difficult to measure in field and hence length
is taken as a proxy for girth. Knowledge of the
length-girth relationships of major species would be
an additional input for designing gears and deriving
an optimum mesh size/shape for trawl codends. The
length-girth relationships of 15 commercially important
species targeted by trawls along Cochin coast
were derived. The results indicated that thirteen of
these species had no significant variation in the
value of slope, whereas for Pampus argenteus and
Trichiurus lepturus, the values for the slope, differed
significantly (p<0.05, t-test) indicating that the mesh
size requirement would be different for these
species. Though estimates did not consider the sex
or condition of the fishes studied, the results of the
study will be an added input for deriving selectivity
estimates
Description
Keywords
Trawling, fish girth, bycatch, mesh size