Population dynamics and stock assessment of deep water rose shrimp Parapenaeus longirostris (Lucas, 1846) from the Mediterranean Coast of Morocco

Abstract

The population dynamics and stock parameters of the deep water rose shrimp Parapenaeus longirostris (Lucas, 1846) was investigated from the Mediterranean coast of Morocco. Length-frequency data were collected from landings of coastal trawlers at M’diq Port on the Moroccan Mediterranean coast over a period of 13 months from April 2017 to April 2018. The estimated growth parameters were CL∞ = 52.87 mm, K = 0.39 yr-1 and to = - 0.35 .Total mortality coefficient (Z) was estimated as 3.49 yr-1 while the natural mortality estimated using two different methods was 1.89 yr-1 and 1.36 yr-1 and correspondingly the fishing mortality was calculated as 1.51 yr-1 and 2.13 yr-1. Yield per recruit and relative biomass per recruit analysis showed that the value of current exploitation rate (E) is 0.68 which is higher than the exploitation rate E 0.5=0.36, which indicates that the stock is currently overexploited. Hence it is advised to decrease the present exploitation rate by 50% of the current level to sustain the fishery.

Keywords: Exploitation,  Mediterranean coast, Morocco, Parapenaeus longirostris, Population dynamics