LEWIS and YERGER: BIOLOGY OF FIVE SEAROBINS 



The occurrence of P. stearnsi in such greater 

 numbers during the day is difficult to explain. 

 Two opposing hypotheses can be postulated. 

 First, P. stearnsi may be a diurnal species, active 

 over the bottom during the day, and perhaps 

 burrowing during the night and thus eluding 

 capture. Or second, P. stearnsi may be nocturnal; 

 during the day it may rest on the bottom exposed 

 to daytime trawls, while at night it may ascend 

 into the water column to feed beyond the reach of 

 the trawl. We favor the second possibility be- 

 cause of the general physiognomy of this species. 

 Food habits, as will be discussed, also suggest a 

 more actively swimming existence compared 

 with other triglids. 



Reproduction 



Sexual Maturity 



Bellator militaris and P. stearnsi are rather 

 small triglids maturing at 65 and 60 mm SL and 

 reaching a maximum size around 120 and 135 

 mm, respectively (Ginsburg 1950). Prionotus 

 alatus, P. martis, and P. roseus mature at about 

 100 mm SL and attain at least 189 mm (Ginsburg 

 1950), 166 mm (Reid 1954), and 225 mm (Gins- 

 burg 1950), respectively. Marshall (1946) found 

 that P. carolinus and P. euolans mature at about 

 140 and 180 mm SL, respectively, and attain a 

 much larger size than any Gulf species. It ap- 

 pears that the size at sexual maturity is largely 



a function of the size attained by the particu- 

 lar species. 



Spawning Season 



Spawning seasons for the triglids collected in 

 this study can be separated into two ill-defined 

 categories: 1) Late summer to fall or early win- 

 ter and 2) late fall to spring or summer (see 

 Figure 5). 



Prionotus stearnsi appears to fit into the first 

 category. In our study ripe females were collected 

 only in October and December. Longley and 

 Hildebrand (1941) reported collecting a ripe fe- 

 male in August off the Tortugas. These limited 

 data and a large number of very small specimens 

 in collections from October, December, and Janu- 

 ary indicate that P. stearnsi probably spawns 

 from late summer to late fall or early winter. The 

 paucity of ripe females suggests that this species 

 may spawn at greater depths than those sampled 

 in this study. 



Three of the remaining four species {B. mili- 

 taris, P. alatus, P. roseus) had obviously pro- 

 tracted spawning seasons from fall to late spring 

 or summer. The presence of a number of small 

 individuals collected throughout the year further 

 corroborated the length of the reproductive 

 period. 



Prionotus martis was in spawning condition in 

 October, December, and April. The presence of 

 only a few juveniles in this study leads us to 



Figure 5. — Spawning seasons for 

 five species of searobins. 



101 



