Depth as a factor in abundance and size of juvenile penaeid shrimps in the absence of estuaries and marshes

Triweekly trawling around low tide during daylight at 1, 2, 3, and 4 m depths along north Kuwait Bay's extensive intertidal mudflats from 1 April 1985 through 9 December 1986 showed the catchability ofMetapenaeus affinis (H. Milne-Edwards, 1837),M. stebbingi Nobili, 1904,Parapenaeopsis stylifera (H. Milne-Edwards, 1837), andPenaeus semisulcatus De Haan, 1844 differed significantly with depth and season. All species were significantly more catchable in 1 and 2 m depths than in 3 and 4 m depths.M. affinis showed the clearest and most consistent relationship with depth: catchability in 1 m depths was significantly greater than that in 2 m depths (24.9 vs 5.4 per 5-min tow), and catchability in 1 and 2 m depths was significantly greater than that in 3 and 4 m depths (15.2 vs 1.4 per 5-min tow).M. affinis also showed the clearest relationship of increasing size with depth. Shrimp captured in 1 m depths were significantly smaller (~ 14 mm carapace length, CL) than those captured in 2 m depths in the spring (~23 mm CL) and summer (~ 18 mm CL). In the absence of low-salinity waters and intertidal vegetation, it is believed that the edge of the advancing and receding tide over the mudflats, i.e. the shallowest waters, provides juvenile shrimp, particularlyM. affinis, protection from predation.