Prionotus Carolinus) and the Striped Searobin (P

Larval and settlement periods of the northern searobin (Prionotus carolinus) and the striped searobin (P. evolans) Item Type article Authors McBride, Richard S.; Fahay, Michael P.; Able, Kenneth W. Download date 26/09/2021 20:14:09 Link to Item http://hdl.handle.net/1834/31043 63 Abstract–This study reports new Larval and settlement periods of the information about searobin (Prionotus spp.) early life history from samples col northern searobin (Prionotus carolinus) lected with a Tucker trawl (for plank tonic stages) and a beam trawl (for and the striped searobin (P. evolans)* newly settled fish) from the coastal waters of New Jersey. Northern searo Richard S. McBride bin, Prionotus carolinus, were much more numerous than striped searobin, Marine Field Station P. evolans, often by an order of mag Institute of Marine and Coastal Sciences nitude. Larval Prionotus were collected Rutgers University during the period July–October and 800 Great Bay Blvd. their densities peaked during Septem Tuckerton, New Jersey 08087 ber. For both species, notochord flexion Present address: Florida Marine Research Institute was complete at 6–7 mm standard 100 Eighth Avenue SE length (SL) and individuals settled at St. Petersburg, Florida 33701-5095 8–9 mm SL. Flexion occurred as early E-mail address: [email protected].fl.us as 13 days after hatching and set tlement occurred as late as 25 days Michael P. Fahay after hatching, according to ages esti mated from sagittal microincrements. Sandy Hook Laboratory Both species settled directly in conti Northeast Fisheries Science Center nental shelf habitats without evidence National Marine Fisheries Service, NOAA of delayed metamorphosis. Spawning, Highlands, New Jersey 07732 larval dispersal, or settlement may have occurred within certain estuar ies, particularly for P. evolans; thus col Kenneth W. Able lections from shelf areas alone do not Marine Field Station permit estimates of total larval produc Institute of Marine and Coastal Sciences tion or settlement rates. Reproductive Rutgers University seasonality of P. carolinus and P. evo 800 Great Bay Blvd. lans may vary with respect to latitude Tuckerton, New Jersey 08087 and coastal depth. In this study, hatch ing dates and sizes of age-0 P. caro linus varied with respect to depth or distance from the New Jersey shore. Older and larger age-0 individuals were found in deeper waters. These varia- Although adult fish assemblages off- iors become evident that allow for delay- tions in searobin age and size appear to shore of the middle Atlantic states ing settlement until suitable juvenile be the combined result of intraspecific are fairly well known (e.g. Edwards, habitat is found (Cowen, 1991; Sponau- variations in searobin reproductive seasonality and the limited capability of 1976; Colvocoresses and Musick, 1984; gle and Cowen, 1994). Ultimately, an searobin eggs and larvae to disperse. Gabriel, 1992), the early life history understanding of the life cycle of any of many of these same species and benthic species is constrained if the set- the function of shelf habitats as nurs- tlement period is not viewed as an inte- ery grounds are poorly understood (e.g. gral transition from the planktonic to Fahay, 1983, 1993; Able and Fahay, the adult period. 1998). Because year-class strength is Our study contributes to an under- believed to stabilize prior to the early standing of how fishes use continental juvenile stage, information about the shelf habitats as nurseries with an ex- transition from the plankton to ben- amination of the early life history of thic (i.e. settlement) habitats should the northern searobin, Prionotus caro- contribute to our understanding of the linus, and the striped searobin, P. evo- population processes of benthic fishes lans. Both are common species in the (Cushing and Harris, 1973; Campana coastal region between Cape Cod and et al., 1989; Myers and Cadigan, 1993). Cape Hatteras, but relatively little is Settlement is regarded as a dynamic known about their early life history ow- period of early development because ing largely to their low economic impor- mortality rates can differ between pre- tance in relation to the heavily exploit- and postsettlement life stages (Sale ed fisheries of this region (McBride et and Ferrell, 1988), dramatic morphological and physiological transforma- * Contribution 2001-28 of the Institute of Manuscript accepted 30 July (2001). tions occur (Youson, 1988; Markle et al., Marine and Coastal Sciences, Rutgers Uni- Fish. Bull. 100:63–73 (2002). 1992; McCormick, 1993), and behav- versity, New Brunswick, NJ 08901. 64 Fishery Bulletin 100(1) al., 1998). Both species are known to begin spawning as early as May and to continue spawning into Octo ber as determined by maturity indices (e.g. Richards et al., 1979; Wilk et al., 1990). Prionotus spp. eggs and larvae are known to be seasonally abundant above the continental shelf and within some estuaries (e.g. Rich ards et al., 1979; McBride and Able, 1994) but eggs and larvae are difficult to identify to species on a rou tine basis. Therefore we took advantage of recently 39°30′ reported morphological information (Able and Fahay, 1998) to examine ichthyoplankton collections. Our study was designed to examine how spawning patterns varied between two congeners, but intraspe cific spawning variation also became evident. A sec 39°25′ ond goal of our study was to examine settlement—to 74°20′ 74°10′ date not reported for either species. Both species un dergo flexion and complete fin-ray development at about 6–8 mm SL (Yuschak and Lund, 1984; Yuschak, Figure 1 1985; Able and Fahay, 1998). Separation of prehensile Map of sampling station locations in southern New Jersey, including rays on the pectoral fin, a major adaptation for ben the main stations at Beach Haven Ridge (landward and seaward: filled thic feeding (Morrill, 1895; Bardach and Case, 1965; circles), other ridge stations (open circles), continental shelf transect stations (filled triangles), and estuarine stations (open triangles). The Finger and Kakil, 1985), occurs in fish as small as 12 state of New Jersey, and the study location, are shown in the inset. mm SL (Yuschak, 1985). Yet settled juveniles <25 mm SL are rare (Lux and Nichy, 1971; Richards et al., 1979; McBride and Able, 1994), which raises the question one minute to complete, but estuarine tows were reduced of whether Prionotus spp. are competent to settle after to 20 or 30 seconds to avoid collecting large volumes of completing fin-ray development or whether they common macroalgae, detritus, shell, etc. Sampling occurred during ly delay settlement. Using a novel combination of sam daylight unless otherwise stated. Details of sampling pro pling gears, we collected a continuum of late larval and cedures are provided by Hales et al.1 Volume or area early juvenile Prionotus spp. to examine settlement di sampled was calculated by using a flow-meter for ichthy rectly. We report for the first time species-specific larval oplankton collections or a meter wheel for beam trawl abundances, distributions, ages, sizes, growth rates, and collections. Larval density is presented as the geometric descriptions of early benthic existence. mean number of fish/m3 for Tucker trawl collections. Juve nile density is presented as the geometric mean number of fish/m2 of sea bottom. Calculations of geometric means Materials and methods follow Sokal and Rohlf (1981). The standard length (SL) of all, or at least 20 fish per Collections were made in coastal waters of New Jersey, tow, was measured after the fish were preserved in 95% specifically near Beach Haven Ridge (Fig. 1, Table 1), a ETOH. The term “larva” was used in reference to individu prominent sand ridge formation that rises to about 8 m als collected in Tucker trawl tows. Preflexion larvae were depth and is surrounded by depths of 14–16 m (Stahl et distinguished from flexion larvae by the absence or pres al., 1974). Sampling frequency at two stations, one land ence, respectively, of cartilaginous urals on the ventral ward and the other seaward of the ridge, was every two to edge of the notochord tip; the development of these urals six weeks from July 1991 to November 1992. Two tows of a accompanied flexion of the notochord tip (Kendall et al., Tucker trawl (1 m2) were made at each station in a double, 1984). Larvae were characterized as postflexion stage once stepped-oblique fashion. One tow was made from the sur the notochord tip moved anterior to the posterior edge of face to the bottom (three minutes duration) and the other the hypurals. tow was fished from the bottom back to the surface (six Daily age was estimated from counts of sagittal otolith minutes). Newly settled juveniles and older fishes were microincrements, which were validated as daily by Mc- sampled with a 2-m beam trawl in Great Bay estuary, near Bride.2 Otoliths with a maximum length less than about Beach Haven Ridge, as well as in other habitats (Fig. 1). The data from these stations were arranged in the follow 1 Hales, L. S., Jr., R. S. McBride, E. A. Bender, R. L. Hoden, ing groups: 1) the two principal ridge stations (described and K. W. Able. 1995. Characterization of non-target inverte above); 2) miscellaneous stations scattered on top of and brates and substrates from trawl collections during 1991–1992 around the ridge; 3) stations along a transect leading at Beach Haven Ridge (LEO-15) and adjacent sites in Great directly offshore from the ridge; and 4) a cluster of stations Bay and on the inner continental shelf off New Jersey. Techni cal report (contribution 95-09), 34 p. Institute of Marine and within nearby Great Bay. Generally, three tows were com Coastal Sciences, Rutgers, The State University of New Jersey, pleted at stations immediately landward and seaward of New Brunswick, NJ.

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