623 



Length-specific brood size and winter parturition 

 in pink seaperch iZaiembius rosaceus) 

 (Perciformes: Embiotocidae) 



Lori H. LaPlante 



California State University Long Beach 



Department of Biological Sciences 



1250BellflowerBlvd 



Long Beach, California 90840 



Present address: Saint Anselm College 

 Department of Biology 

 100 Saint Anselm Drive 

 Mancfiester, New Hampshire 03102 



Email address llaplante a anselm edu 



The viviparous pink seaperch iZalem- 

 bius rosaceus) is considered unusual 

 among other embiotocids because of 

 its deep-water habitat (Tarp. 1952), 

 winter parturition (Goldberg and Tic- 

 knor, 1977), small brood size (Baltz, 

 1984), and apparent lack of a posi- 

 tive relationship between brood size 

 and female size I Baltz, 1984). In the 

 present study, I present further sup- 

 port that parturition in pink seaperch 

 occurs in winter and new evidence 

 indicating length-specific brood sizes 

 in the species. 



Pink seaperch are found in deep 

 water (to 229 m: Miller and Lea, 

 1972) over soft bottom (Allen, 1982) 

 year-round off the coasts of Califor- 

 nia and Baja California (Eschmeyer 

 et al., 1983). Mating occurs in spring 

 and parturition occurs in winter 

 (Goldberg and Ticknor, 1977)— a 

 unique breeding schedule among 

 surfperches. Other surfperches mate 

 in summer or fall and give birth the 

 following spring or summer when 

 food for offspring is plentiful. For 

 reasons that remain unclear, brood 

 size for pink seaperch is considered 

 low (mean = 3.5: Goldberg and Tic- 

 knor, 1977) compared to other small- 

 size (<160 mm) surfperches (reviewed 

 in Baltz, 1984). 



A positive relationship between 

 brood size and female size is gener- 

 ally the rule among fishes (Bagenal, 

 1978) and is observed in all surf- 

 perches with the exception of pink 

 seaperch (Baltz, 1984). However, 

 data for the species are dubious 

 because near-term females tend to 

 abort their young during the time of 



collection (Baltz and Knight, 1983; 

 Baltz, 1984) — a behavior that can re- 

 sult in both underestimates in brood 

 sizes and high variability in length- 

 specific brood size. 



The goal of this study was to eval- 

 uate characteristics of the reproduc- 

 tive biology of pink seaperch using 

 samples taken during periods both 

 early and late in the breeding sea- 

 son. I predicted that estimates in 

 length-specific brood size for females 

 collected later in the season should 

 be significantly smaller than those 

 collected earlier if, in fact, near-term 

 females have a high probability of 

 aborting embryos. Similarly, I ex- 

 pected to see higher variability in 

 relationships between length-specif- 

 ic brood size and female size in the 

 late, compared to early, period of the 

 breeding season. 



Materials and methods 



Specimens of female pink seaperch 

 were collected with a 7.6-m (head- 

 rope) otter trawl with 1.3-cm codend 

 mesh on the Palos Verdes shelf near 

 Point Fermin, CA (33°41'N, 118°19'W) 

 in fall (September and October, at 

 54 and 60 m depth, respectively) 

 1994 and in winter (January, at 66 

 m depth) 1995. Females were distin- 

 guished from males by having either 

 a rounded belly or by lacking a fleshy 

 reproductive organ on the anterior 

 portion of the anal fin (Tarp, 1952). 

 Gravid females collected in winter 

 were stored separately in sealable 

 bags to ensure that any embryos sub- 



sequently born were included in brood 

 size records; females collected in fall 

 had no evidence of premature births 

 nor were there any premature embryos 

 present in fall collections (see Results 

 section). Individuals were placed on 

 ice, frozen, and processed within 10 

 days. Females were dissected and the 

 following information was recorded: 

 standard length (SL ±1 mm), body 

 mass (±1 g), brood size, embryo SL 

 (±1 mm), embryo mass (±0.01 g), and 

 evidence of premature birthing. From 

 the appearance of females that had 

 evidently expelled their broods while 

 in storage bags, I recorded a female as 

 having prematurely given birth if her 

 ovary was devoid of embryos, flaccid, 

 and contained traces of fresh blood. 

 The relationships between female and 

 brood size for fall and winter were 

 analyzed separately by using regres- 

 sion analyses (SPSS, vers. 10, SPSS, 

 Inc., Chicago, IL). Females showing 

 evidence of recent expulsion were not 

 included in brood size analyses. 



Results 



The size distribution of females cap- 

 tured varied between seasons (Fig. 1). 

 The mean standard length (SL) of 

 females in fall and winter was 125 

 mm (±15 mm SD, n=21) and 96 mm 

 (±21 mm SD, ;j=76), respectively, and 

 this difference was significant (/-test: 

 ? = 6.82, df=101, P<0.001). All females 

 greater than or equal to 100 mm SL 

 (;?,,,, 1 = 26, "„.inttr=31' were sexually 

 mature, having either embryos or evi- 

 dence of recent expulsion of embryos. 

 Among the mature females, the mean 

 SL in fall and winter was 127 mm 

 (±14 mm SD, ;!=26) and 117 mm 

 (±9 mm SD, a? = 31), respectively, and 

 this difference was also significant 

 (f-test; ^=3.19, df=55, P=0.002). 



Both mean brood size and the re- 

 lationship between female size and 

 brood size varied between seasons 

 (Fig. 2A). Mean brood sizes in fall 

 and winter were seven (±3 SD) and 

 three (±1 SD), respectively, and this 



Manuscript submitted 21 March 200.5 

 to the Scientific Editor's Office. 

 Manuscript approved for publication 

 21 November 2005 by the Scientific Editor. 

 Fish. Bull. 104:623-62512006). 



