Stock assessment of Hooghly Croaker Panna heterolepis in the Bay of Bengal (Southern Bangladesh): implications for sustainable management

Abstract

The study describes growth pattern, growth parameter, mortality, recruitment pattern, exploitation rate ( E) and maximum sustainable yield (MSY) to Panna heterolepis from the Bay of Bengal (Bangladesh). About 1223 specimens were collected from commercial fishermen for 12 consecutive months from January to December, 2019. Length–frequency data were analyzed with FAO-ICLARM Stock Assessment Tool. Moreover, our study recorded different water quality and environmental parameters including pH, rainfall, temperature and DO (dissolved oxygen) from the Bay of Bengal. The findings of the study revealed that the allometric co-efficient ( b ) value indicated negative allometric growth (<3.00) for P. heterolepis population. Whereas, the population dynamic parameters showed growth coefficient ( K ) 0.13 year −1 , life-span ( t max ) 3.85 year and growth performance index ( Ø′ ) 2.30. Along with this, P. heterolepis was found to grow rapidly with an asymptotic length ( L ∞ ) of 39.08 cm. We found that the natural mortality ( M = 0.44 year −1 ) rate was almost similar with fishing mortality ( F = 0.42 year −1 ). Consequently, the standing stock was not quite sustainable with the existing fishing strategy. Furthermore, the maximum allowable exploitation rate ( E max = 0.471) was lower than the recorded exploitation rate ( E = 0.490). Subsequently, overfishing is the most focal threat to the wild stock. The recruitment pattern was almost continuous throughout sampling period. Finally, the MSY was assessed at 10234.47 metric tons. Additionally, the environmental parameters denoted that the ecosystem was in a balanced condition for the wild population. The findings would be very useful to introduce appropriate fishing regulations in the Bay of Bengal and nearby ecosystem.

Fisheries Reference Point and Stock Status of Croaker Fishery (Sciaenidae) Exploited from the Bay of Bengal, Bangladesh

“…It may be assumed that the fishery was in overfished condition, but the high growth rate and reduction in fishing efforts may contribute to the fishery rebuilding a sustainable stock. Several previous studies reported an assessment of the stock of Panna heterolepis, Pennahia anea, Jhonius argentatus, Johnieops vogleri, and Johnius argentatus from the BoB waters, Bangladesh [1][2][3]5]. Additionally, the population dynamics of Otolithoides pama from the Sundarbans area of Bangladesh was studied [9].…”

“…Croakers, locally called Jewfish or Poa mash, are among the largest groups of commercially important fishes exploited from Bangladesh's Bay of Bengal (BoB) water [1][2][3]. Croakers are under the Perciformes order and belong to the family Sciaenidae [4].…”

“…The most abundant species of croaker are Johnius belangerii (Belanger's croaker), J. elongates (Spindle croaker), J. dussumieri (Bearded croaker), Otolithes cuvieri (Lesser tiger-tooth croaker), Otolithoides pama (Pama croaker), Pennahia anea (Greyfin croaker), and Protonibea diacanthus (Spotted croaker). These seven species of croakers play a vital role in Bangladesh's national economy [3,5].…”

“…Croakers are bottom-dwelling carnivore fishes distributed in the shallow coastal and marine waters of the BoB. While juvenile croakers are found in coastal water, adults can 2 of 12 move toward shallow water of the BoB, where maximum commercial fishing occurs [3,4]. They are harvested by artisanal and industrial fishers in which the fishery is caught by bottom trawl, gillnet, and long lines [5].…”

“…Because of different management and conservation measures, the natural stock of croaker has been progressively improving since 1990 [8]. However, there are minimal studies on the growth pattern, mortality, and length-weight relationships of a few croaker species, but no comprehensive information on the stock condition of croaker in the BoB [1][2][3]5,7,9,10].…”