142 



Abstract— Life history aspects of larval 

 and, mainly, juvenile spotted seatrout 

 tCynoscion nebulosus) were studied 

 in Florida Bay. Everglades National 

 Park, Florida. Collections were made 

 in 1994-97, although the majority of 

 juveniles were collected in 1995. The 

 main objective was to obtain life history 

 data to eventually develop a spatially 

 explicit model and provide baseline 

 data to understand how Everglades res- 

 toration plans (i.e. increased freshwater 

 flows) could influence spotted seatrout 

 vital rates. Growth of larvae and juve- 

 niles (<80 mm SL) was best described 

 by the equation log, standard length 

 = -1.31 + 1.2162 (log,, age). Growth in 

 length of juveniles (12-80 mm SL) was 

 best described by the equation standard 

 length = -7.50 + 0.8417 (age). Growth 

 in wet weight of juveniles (15-69 mm 

 SL) was best described by the equation 

 log c wet-weight = -4.44 + 0.0748 (age). 

 There were no significant differences 

 in juvenile growth in length of spot- 

 ted seatrout in 1995 between three 

 geographical subdivisions of Florida 

 Bay: central, western, and waters adja- 

 cent to the Gulf of Mexico. We found a 

 significant difference in wet-weight for 

 one of six cohorts categorized by month 

 of hatchdate in 1995. and a significant 

 difference in length for another cohort. 

 Juveniles (i.e. survivors) used to cal- 

 culate weekly hatchdate distributions 

 during 1995 had estimated spawning 

 times that were cyclical and protracted, 

 and there was no correlation between 

 spawning and moon phase. Tem- 

 perature influenced otolith increment 

 widths during certain growth periods in 

 1995. There was no evidence of a rela- 

 tionship between otolith growth rate 

 and temperature for the first 21 incre- 

 ments. For increments 22-60, otolith 

 growth rates decreased with increas- 

 ing age and the extent of the decrease 

 depended strongly in a quadratic fash- 

 ion on the temperature to which the 

 fish was exposed. For temperatures at 

 the lower and higher range, increment 

 growth rates were highest. We suggest 

 that this quadratic relationship might 

 be influenced by an environmental 

 factor other than temperature. There 

 was insufficient information to obtain 

 reliable inferences on the relationship 

 of increment growth rate to salinity 



Manuscript approved for publication 

 23 June 2003 by Scientific Editor. 



Manuscript received 20 October 2003 

 at NMFS Scientific Publications ( >ffice. 



Fish. Bull. 102:142-155 (2004). 



Growth, mortality, and hatchdate distributions 

 of larval and juvenile spotted seatrout 

 {Cynoscion nebulosus) in Florida Bay, 

 Everglades National Park 



Allyn B. Powell 

 Robin T. Cheshire 

 Elisabeth H. Laban 



National Ocean Service 



National Oceanic and Atmospheric Administration 



Center for Coastal Fisheries and Habitat Research 



101 Pivers Island Road 



Beaufort, North Carolina 28516 



E-mail address (for A. B Powell): allyn powellgnoaa gov 



James Colvocoresses 



Patrick O'Donnell 



Florida Fish and Wildlife Commission 

 Florida Marine Research Institute 

 2796 Overseas Highway, Suite 119 

 Marathon, Florida 33050 



Marie Davidian 



Room 209, Patterson Hall 

 2501 Founder's Drive 

 North Carolina State University 

 Raleigh, North Carolina 27695 



The spotted seatrout (Cynoscion nebu- 

 losus) is an important recreational fish 

 in Florida Bay and spends its entire life 

 history within Florida Bay I Rutherford 

 et al.,1989). The biology of adult spotted 

 seatrout in Florida Bay is well known 

 (Rutherford et al., 1982, 1989), as are the 

 distribution and abundance of juveniles 

 in the bay, including a description of the 

 juvenile habitats and their diets (Het- 

 tler, 1989; Chester and Thayer, 1990; 

 Thayer et al., 1999; Florida Department 

 of Environmental Protection 1 ). The 

 temporal and spatial distribution and 

 abundance of larval spotted seatrout in 

 Florida Bay and adjacent waters, and the 

 spatial and temporal spawning habits of 

 these larvae also have been determined 

 (Powell et al., 1989; Rutherford et al.. 

 1989; Powell, 2003). 



The early life history of spotted 

 seatrout in other south Florida estu- 

 aries also has been well documented. 

 Peebles and Tolley ( 1988) described the 

 distribution, growth, and mortality of 

 larval spotted seatrout in Naples and 



Fakahatchee Bays, and McMichael and 

 Peters (1989) described the size distri- 

 bution, growth, spawning, and diet of 

 spotted seatrout in Tampa Bay. 



Information on growth and mortality 

 of larval and juvenile spotted seatrout 

 in Florida Bay is lacking. Research on 

 these topics would enhance our under- 

 standing of the entire life history of this 

 valuable species, and in particular aid 

 in eventually developing a spatially ex- 

 plicit model for spotted seatrout that is 

 highly desired by the Program Manage- 

 ment Committee for the South Florida 

 Ecosystem Restoration Prediction and 

 Modeling Program. In addition, these 

 life history studies could help clarify ju- 

 venile growth and survival and provide 

 needed information for the restoration 



Florida Department of Environmental 

 Protection. 1996. Fisheries-independent- 

 monitoring program. 1995 annual report, 

 58 p. Florida Department of Environmen- 

 tal Protection, Florida Marine Research 

 Institute, 100 8 th Avenue SE, St. Peters- 

 burg, FL 33701. 



