Figure 1.— Transects (lettered) and collecting stations (num- 

 bered) of 1965-66 plankton survey between Cape Cod and 

 Cape Lookout. 



intervals and increased the towing time at each interval for 

 net 2. The tow profile for net 1 was similarly adjusted in 

 depths less than 15 m (Smith 1973). 



Because of variations in the towing time at 3-m depth 

 intervals between inshore and offshore stations, it was 

 necessary to standardize tows to obtain measures of relative 

 abundance. A standard tow consisted of one or both nets 

 fishing for 5 min at each of the six depth intervals within its 

 vertical sampling range. We adjusted the catches to 

 equalize sampling effort at all depth intervals when either 

 net was limited to sampUng at less than six intervals. For 

 example, when a net fished at only three intervals during 

 the 30-min tow, the catch was halved. When two intervals 

 were fished, it was reduced by two-thirds. We combined the 

 adjusted catches of nets 1 and 2 at stations where both nets 

 fished simultaneously. All catches discussed are adjusted. 



If more than 100 larvae of a species were caught at a 

 station, we usually measured a subsample of 25 randomly 

 selected specimens to the nearest 0.1 mm and adjusted the 

 number measured to coincide with the total catch, which we 

 recorded in size increments of 1.0 mm. 



In spite of the possibility of year-to-year variations in the 

 onset, duration, and success of spawning, data collected 

 during the two calendar years of the survey were combined 

 and treated as a single complete spawning season for each 

 species. For example, we discuss results of fall and winter 

 spawning by beginning with the October and November 

 1966 catches, and continue with results of December 1965, 

 January 1966, etc. We determined monthly shifts in 

 spawning grounds and the duration of spawning by plotting 

 the distribution of larvae by size categories, provided larvae 

 occurred in sufficient numbers to merit such analyses. 

 Figures showing the distribution of larvae by cruise include 

 damaged larvae that could not be measured, but tables and, 

 of course, those figfures depicting the distribution of larvae 

 by size categories do not. Thus, the number of larvae in the 

 tables and the figures showing the distribution of larvae by 

 size do not always correspond with the figures showing the 

 distribution of all larvae collected on a cruise. If we caught 

 only a few larvae of a species, a figure showing their distri- 

 bution for that cruise may not be included. These larvae are, 

 however, included in the composite figure, or that figure 

 showing the combined catch for all cruises on which we 

 caught larvae of a particular species. Thus, the composite 

 figure for a species may show larval occurrences that are 

 not evident on other figures. 



Because larvae hatch and metamorphose at sizes that are 

 intraspecifically similar but interspectfically different, the 

 size categories vary between species. We assumed that the 

 spawning grounds for each species were represented by the 

 area encompassing stations where we caught small larvae. 

 The spawning season included months when small larvae 

 occurred in our samples. 



ENVIRONMENTAL INFLUENCES ON 

 THE DISTRIBUTION OF FISHES 



Both water temperature and salinity undergo pronounced 

 seasonal changes within the bight, due mostly to changes in 

 weather and runoff from the numerous adjacent estuaries. 

 Water temperatures increase rapidly during the spring. 

 Warming begins inshore along the southern end of the bight, 

 and progresses northward and seaward as cold winter winds 

 give way to warm spring and summer breezes (Norcross and 

 Harrison 1967). A seasonal thermocline develops through- 

 out most of the bight by summer, and the water column 

 remains thermally stratified until fall. A unique cell of cold 



