Larvae pass through two planktonic forms in one to two weeks prior to 

 becoming sessile attached postlarvae. Bay scallop postlarvae attach to sea- 

 grasses for several weeks before taking on the appearance and lifestyle of 

 adults. Postlarval calico scallops attach to large shells and hard substrate 

 prior to becoming mobile juveniles. Postlarval calico scallops are deposited 

 in "windrows" that follow local current patterns. 



Postlarval bay scallops settle in grass beds in shallow water whereas 

 post larval calico scallops settle in water 10 to 40 fathoms deep offshore. 

 They move randomly within these general areas. Bay scallops grow from several 

 mm to about 60 mm from winter through summer and reach sexual maturity by 

 fall. Calico scallops show similar growth rates from summer through winter 

 and reach sexual maturity by early spring when about 60 mm. 



Bay scallops live in most Florida estuaries, but the largest populations 

 are in St. Joe Bay, and near Anclote Key, north of Tampa Bay. Bay scallops 

 once were common in Pine Island Sound until the population was reduced by a 

 combination of red tides and habitat alterations (particularly dredge and fill 

 operations in the 1950' s and 1960's). Calico scallops live in most offshore 

 areas of Florida, but are most abundant near Apalachicola Bay and Cape Canav- 

 eral. Bay scallops generally live in the same bay system each year, whereas 

 the location of calico scallop beds may vary each year, depending upon where 

 the postlarvae are deposited. Maximum age is about two years. Nearly all die 

 after spawning. Scallops are filter feeders, consuming microscopic phyto- 

 plankton. 



The monthly landings of scallops on the west coast of Florida in 1965, 

 1970, and 1975 are given in Table FSH-40 in the Data Appendix. 



PROBLEMS OF RESEARCH AND DEVELOPMENT 



THE STATUS OF RESEARCH 



In the early 1900's very little was known about the biology of the major 

 sport and commercial saltwater and estuarine fishes of Florida. Following 

 World War II, interest in fishing as a vocation and an avocation began to 

 increase and with it the need to understand the natural history of the more 

 important species. 



In the 1950' s and 1960's, many papers were written about a variety of ma- 

 rine resource topics. Collectively from these and other more recent reports, 

 major concepts began to emerge concerning the living marine resources. Most 

 significant among these was the estuarine dependency of over three- fourths of 

 the major commercial and sport species. Studies of these species indicated 

 that at least part of their life cycles depended upon the shallow estuarine 

 areas (nursery grounds) where food and protection for young fish or shellfish 

 abounded in a variety of forms. The biological richness and importance of 

 these nursery grounds were difficult to convey to the general public, and 

 thousands of acres were lost to indiscriminate dredging and filling before 

 protective legislation was finally passed. 



20b 



