About 36 species of shrimps have been recorded from the marine waters of Bangladesh. Among the penaeid shrimps Penaeus monodon, P. semisulcatus, P. japonicus, P. indicus, P. merguensis, Metapenaeus monoceros, M. brevicornis, M. spinulatus, Parapenaeopsis stylifera, Parapenaeopsis sculptilis and Solenocera indica are the most exploited species. Brown shrimp, M. monoceros alone contributes about 56% of the total shrimp catch. While, the tiger shrimp, P. monodon is the main commercial important species because of its export value and price. Total shrimp harvest (capture fishery) from the coastal and marine sector in 2000-01 was 31,037 t, of which only 10% was contributed by the industrial trawlers and the rest was contributed by the small-scale artisanal fishery. Shrimp harvest steadily increased every year and reached to 56,989 t in 2010-11, of which about 5% was contributed by the industrial trawls and the rest 95% was contributed by the artisanal fishery. The increase in total shrimp harvest during these 11 years is around 83.6%. Mean contribution (industrial and artisanal combined) of all shrimps to total marine fish production during 2000-01 to 2010-11 was around 9.0%.
Comparative catch of industrial trawls during 2005-06 and 2010-11 revealed that in these six years catch of of shrimps decreased from 10% to 7%. The trawler fleets exploit the following key shrimp and fish species: P. monodon, P. merguiensis, P. indicus, Metapenaeus monoceros, M. brevicornis, pomfrets, haittails, goatfish, catfish, croakers, Bombay duck and lizard fish. Catch of unsorted other fishes increased from 68% to 86% during these six years. As the statistics show total industrial trawlers' catch gradually increased from 34,084 t in 2005-06 to 41,665 t in 2010-11, it seems that decreased percentages of shrimps during these six years are simply due to statistical changes of unsorted other fishes. When the total catches (t) of industrial trawlers were plotted year-wise against group-wise of fishes for these six years it confirmed the skewed impact of unsorted other fishes on the catch composition. Artisanal catch gradually increased from 445,726 t in 2005-06 to 504,668 t in 2010-11, about 13.22% increment in these six years. During these six years catch percentages of shrimps remained unchanged within 10-11%. Maximum landing of shrimps (all marine shrimp species combined) 65,989 t was recorded in 2010-11 and the average landing during the last two years (2010-11 and 2011-12) was 61,824.5 t which is 93.69% of the maximum landings. Hence shrimps can be included under the class 'abundant' with respect to its present status of exploitation. Its percentage growth was -0.14% during 2002-03, -1.86% during 2008-09 and 1.18% during 2011-12.
Abundance of gravid tiger shrimps (P. monodon), especially the mother-shrimps used as bloodstocks in shrimp hatcheries have declined in terms of CPUE (50% reduction since 1987) and size (22% reduction over the past few years). As a result the major mother-shrimp supplier– the shrimp trawlers very often encroaches into inshore waters (i.e. from >40 m depth zones to as shallow as 10 m) to maintain catches of mother shrimp. At present excessive bottom trawling by the shrimp trawlers have thought to destroyed the shrimp grounds of our Bay. Therefore, it is essential to fix harvest limitation and control strategy to control mother-shrimp harvest and use by the shrimp hatcheries rationally. Assessment of the yearly exact requirement of the P. monodon PL for the culture sector and the mother-shrimp needed thereof is of utmost importance. In order to limit indiscriminate harvesting, save and conserve the mother-shrimps, a sort of total allowable catch (TAC) for each shrimp trawler and total allowable mother-shrimps to be used by each shrimp hatchery (as per respective hatchery's PL production capacity) need to be urgently fixed. In addition a fresh assessment of mother-shrimp grounds are very essential.