International Journal of Marine Science 2016, Vol.6, No.44, 1-8
7
Pandian et al., 2005 obtained high value L∞ (75.05) and K (0.96) in the upper east coast of India. Prathibha Rohit
& Shubhadeep Ghosh, 2012 studied the growth parameters in the Indian waters and reported the L∞ and K as
61.27 and 1.4 per year respectively by ELEFAN I. The same data was analyzed by Powell and Wetherall plot too
and it gave a similar value for L∞ 60.19 cm. Present values of L∞ and K estimated by ELEFAN I were 64.2 and
per 0.7/ years respectively and by Powell-Wetherall plot 45.51 and 0.4/year respectively. Observed mid length of
the specimens recorded was 58.5 cm and the predicted extreme length is 62.5 cm, hence the value obtained for L∞
by Powell-Wetherall plot i.e., 45.51 cm appears unrealistic. The value obtained by ELEFAN I appears to be more
appropriate.
Kasim and Abdussamad (2002) studied the mortality parameters of the species in the east coast of India and
reported the mean natural mortality as 1.50, fishing mortality as 5.02 and total mortality as 6.52. Pandian et al.
(2005) obtained the natural mortality as 1.32 /year. Pratibha Rohit and Subhadeep Ghosh (2012) obtained the M, F
and Z values as 1.79, 2.92 and 4.71 respectively. All these studies indicate that the fishing pressure is more on the
species in both the coasts. In the present study, the natural mortality was 1.43, fishing mortality was 1.28 and total
mortality was 2.71 which suggests that the present exploitation level is optimum, however more fishing effort will
have an adverse effect on the fishery. Pratibha Rohit et al., 2012 reported the longevity of the species as 2 years.
Taking Z = 2.71 the t
max
(Hoenig’s, 1983) was computed to be 2 years in the present study. In the first six month
period the growth rate of the species was maximum (4.1 cm/ year) and it decreased in the subsequent six month
period indicating maximum growth of the species in the first six month period itself in the north east coast of
India.
Kasim et al.,
(2002) reported the peak recruitment period for the species during March-April followed by
December in the east coast of India. Previous studies (Kasim et al.,
2005) indicated the recruitment period of the
species in the east coast from October to June with peak period during February - May. Pratibha Rohit and
Subhadeep Ghosh (2012) reported a unimodal recruitment pattern with the young ones being recruited to the
fishery for most of the months of the year. They indicated the peak recruitment during February to July. In the
present study six stages of maturity for the species was obtained and it could be seen that the recruitment period
was between January-July with peak during May. The smallest length of recruit was 16.1cm. The present
observation agrees well with the previous studies.
VPA was studied by various researchers and it indicates that loss in the stock was due to natural causes alone was
up to 34cm (Kasim, 2002). In the present study however indicated that the natural cause of mortality alone in the
stock was up to 28cm. The fishing pressure started at 28.1cm midlength and it increased steadily up to 58.1cm
midlength. The fishing pressure was intense at 37-49cm and 55-58cm. The present observation is indicative of
exploitation of smaller specimens in the fishery.
Naik et al.,
1998 studied the gut contents of the seer fish in the mid-west coast and found that 46.1% of the fishes
were empty stomach and these species are piscivorous in nature with
Stolephorus spp.
as the dominant item in the
gut. Pratibha Rohit and Subhadeep Ghosh (2012) recorded anchovies, scads and sardines in the gut in almost all
the months. In the present study also similar observations were made. 56.2 % of the stomachs were empty and the
preferred food items were mainly anchovies, sardines and shrimps etc.
The present study indicates an unusual sex ratio i.e dominance of female in the higher length groups need to be
studied more elaborately. Also the fishing mortality is less than the natural mortality which could be due to
predation, starvation etc. 56% of the specimens studied was found to be empty stomach is supportive of this.
Present trend in fishery in northeast coast is mainly multispecies and also resource specific gear for seerfish is not
operated here. Hence to arrive at the stock structure of the species the biological as well as the growth parameters
need to be taken as inputs in various methods and models duly taking into consideration the environmental
parameters and other natural causes affecting the fishery.
