402 U. S. BUREAU OF FISHERIES 



stationed at St. Augustine, Fla. From living and preserved material 

 these species of shrimp have been traced through the egg, nauplius, 

 zoea, and mysis stages of development. It was essential that the eggs 

 and young be distinguished before any clear-cut conception of their 

 early life histories could be possible. It is interesting that the 

 peneids undergo more molts and stages of growth than any other 

 group of decapod crustaceans. Nevertheless probably no complete 

 series of larval forms has yet been traced out for any single species 

 of the Penaeidae. The present studies on eggs and young of these 

 commercially important shrimps not only establish the distinctive 

 morphological features during larval life, but also contribute signifi- 

 cantly to our knowledge of the spawning season and the distribution 

 of the young. 



Observations at St. Augustine and Fort Pierce, Fhi., have proved 

 definitely that many eggs and planktonic young of these two species 

 of commercial shrimp come into the shallow estuarian rivers and 

 lagoons from the ocean through the various inlets. The spawning 

 season along the Georgia and Florida coasts, as previously indicated 

 by examination of ripe adults, extends at least from March into 

 September for the common shrimp, and probably throughout the 

 year for the grooved shrimp, which appears to be a more charac- 

 teristically offshore and deeper water species. 



During the coming year intensive study will be made on the living 

 eggs and young of these southern shrimps to ascertain among other 

 things the rate of development at various stages, the rapidity of the 

 natural movement of young, and the possible factors influencing 

 mortality. 



Migrations. — Kegular sampling of the shrimp population along 

 the South Atlantic coast aboard Fisheries Launch 58 Avas continued 

 by W. W. Anderson for the first 6 months of 1935. The territory 

 covered extended from Cape Komain, S. C, to Cape Canaveral, Fla. 

 As in previous years, nine outside and two inside stations were vis- 

 ited regularly once each month. The particular area covered rep- 

 resentsby far the greater portion of the shrimp-fishing localities 

 on the South Atlantic coast. The stations w^ere so established as to 

 be from 35 to 50 miles apart and to cover the more important fishing 

 centers along the coast, in this way giving us a fairly representative 

 sample of the entire fishery. At each station at least two hauls of 

 1/2-hour duration each were made with a 50-foot otter trawl. Plank- 

 ton tows were made and water temperatures and salinities recorded 

 for every station. Shrimps from each haul were measured and the 

 stages of gonad development observed. All fishes taken in the hauls 

 w^ere recorded as to species and numbers. During the last 6 months 

 of the year such sampling was discontinued in stations north of 

 Brunswick, Ga., but maintained from Brunswick, Ga., to Cape Cana- 

 veral, Fla. 



As mentioned in the previous annual report, the data gathered 

 aboard Launch 58 indicated quite definitely that a migration of 

 shrimp occurs along the South Atlantic coast. During the fall and 

 winter of each year it was observed that large shrimp disappear 

 from the Georgia coast. At the same time an important fisliery for 

 such large shrimp developed ofi' the central Florida coast from St. 

 Augustine to Cape Canaveral. These two facts suggested four pos- 



