PLANKTONIC FISH EGGS AND LARVAE OF NARRAGANSETT BAY. Sidney S. Herrnan

Transcription

1 PLANKTONIC FISH EGGS AND LARVAE OF NARRAGANSETT BAY Sidney S. Herrnan Narragansett Marinc Laboratory, University of Rhode Island ABSTRACT Planktonic fish eggs and larvae were collected weekly at 4 stations in Narragansett Bay, over a period of one year from March 57 to March 958. Thirty-six species of fish eggs and larvae were identified. The peak in spawning activity occurred from late May through mid-august. The peak of fish egg production occurred in June and July, and the period of low abundance occurred between September and February. Peaks of larval abundance were found in July and August and again in January and March. Deeper areas in the Bay contained greater concentrations and a greater variety of species than did the shallow arcas. INTRODUCTION Prior to this study, three surveys of pela,gic fish eggs and larvae have been completed in the coastal waters of southern Nlew England: Pcrlmutter (939) in Long Island Sound, Merriman and Sclar ( 952) in Block Island Sound, and Wheatland (.956) in Long Island Sound. The survey of Narragansett Bay, reported here, was bcgun in early 957 and carried on for a full yearly cycle. Common names of fish idcntified are used in text; specific names appear in the tables. The author is indebted to Dr David M. Pratt and Dr Saul B. Saila of the Narragansett Marine Laboratory for their direction and assistance during the problem and in preparing the manuscript. Aid in identification was given by Mrs Sarah Richards of the Bingham Oceanographic Laboratory, Yale University, and by the staff of the U, S. Fish and Wildlife Service at Woods Hole, Massachusetts. Narragansett Bay is an estuary of square miles, emptying on the south into Rhode Island Sound. The bay has three north-south interconnected passages: the West Passage, East Passage, and Sakonnet River (Fig. -~ ). The circulation of the bay IL Contribution No. 5 from the Narragansett Marine Laboratory of the University of Rho& Ishmd. This study was aided by the Office of Naval Rcscarch, Contract NR 83-54, and the U. S. Fish and Wildlife Scrvicc. :! Present address, Dept. of Biology and Marinc Scicncc Ccntcr, Lehigh University, Bcthlchem, Pennsylvania. is typically estuarine, that is, having a twolayered transport system. A complete description of the physical oceanography of the area is given by Hicks ( 959). METHODS Four stations were selected ( Fig. ) : station, with a depth range of 2 to 3 m, and station 2, with 9 to 9 m, represent the more saline waters sampled, station being the more typical of waters found at the mouth of the bay. At station 3 ( 8 to 4 m ) salinities are variable and a strong current is almost always present. Station 4 (6 m ), represents the least saline situation. Two types of sampling equipment were used simultaneously: a meter net, with a flow meter attached in the mouth, for the larvae, and a Clarke-Bumpus sampler for the eggs. Weekly oblique hauls were made at each of the 4 stations from March 957 to March 958. The nets were towed at a speed of 2 knots. Surface and bottom temperatures were recorded and water samples were collected for salinity determination. The most useful references as aids to identification were Ehrenbaum ( 99)) Kuntz and Radcliffe ( 97), Dannevig ( 9S), Hildebrand and Cable ( 93,934, 938), Perlmutter ( 939), Mcrriman and Sclar ( 952), and Wheatland ( 956). RESULTS Environment Surface salinity values at the four stations ranged from 2.85 to 32.52g (Fig. 2). It should be noted that the summer and early 3

2 4 SIDNEY S. HERMAN 26 STATION I,.,#,I,.8 I,,,,, I,.,.,.,,,.,..,,,..,,..,,..,,.,,, v v I I,,,,I,,,,,,,,,,,,I,,,I,,,,,,,,,,,I,,,,,,,,, APRIL MAY JUNE J LY Au? YPT OCT NO OEC JAN FE@ MARCH TIME OF YEAR (MONTHS) FIG. 2. Surface and bottom salinities. Solid line -surface; broken line-bottc n. FIG.. Fish eggs and larvae station locations. Mean annual figures for Narragansett Bay, based on daytime hauls, show 3.88 fall were unusually dry and salinity values eggs/m3 of water and.3 larva/m3 of were correspondingly higher than average It is probable, l- lowever, that the (S. D. Hicks; personal communication). vater* During the major portion of the spawning season ( see below ), the salinity values J ranged only from 29.2 to 32.52s. The bottom salinity range for all stations was to 32.84%. Surface temperatures measured at the II~~~I~~~~II~~I~I~I~III ~ stations ranged from -2.O C to 24.4 C (Fig. F 25 3 ). Bottom temperature ranged from -2. C 5 to 23.8 C. Spawning cycle STATION 2 E -5-,,,,,,,,,,,,,,,,, (,,,,,,,,,,,,, 3 Eggs were most abundant between June i 25 and July and most scarce from September E through February ( Fig. 4). $ I:; <,; Larvae were most abundant between g -5- July and August and in January and March. C 25 I IIowever, in the July-August period, abun-,5 n# yi dance was due to some 8 species which 5- were usually taken during each haul, STATION 4 whereas the abundance in January and bprl MAY IJUNE(JULY AUG.]SEPT~ OCT. I NOV. I DEC ) JAN FEB. PARCH March was due entirely to the larvae of the American sand launce and the s&pin. The TIME OF YEAR (MONTHS) period of low abundance for larvae was FIG. 3. Surface and bottom tcmpcraturcs. from September through December. ljnc-surface; broken line-bottom. Solid

3 FISH EGGS AND LARVAE OF NARRAGANSETT BAY 5 APRlL MAY JUNE JULY AUG. SEPT. OCT. NO DEC. JAN. FEB. MARCH TIME OF YEAR (MONTHS) FIG. 4. Total number of fish eggs and larvae par cubic meter of water. Solid line-fish eggs; broken lint-fish larvae. figure for larvae represents the minimum value, since day and night replicate hauls made in July 957 indicate a larval ratio of 9 to in favor of the night hauls. Daytime samples were usually collected between 8 and 3. #Station produced the highest catches, both in actual numbers and number of splecies of larvae. However, certain of the species such as northern pipefish, northern puffer, bay anchovy, winter flounder, Atlantic silverside, and goby are shoal water spawners and, therefore, eggs and larvae of these species were more often found in the shallower areas of stations 3 and 4. Some species such as Atlantic cod, sculpin, northern sand launce, and rock gunnel were equally distributed at each of the four stations. Although station had the greatest number of species of fish eggs, in actual numbers station 2 was the most productive. Species composition Table lists, by common and specific names, the 36 species of fish eggs and larvae taken during the 52-week sampling period. Of these, 6 were represented as both eggs and larvae, 8 as larvae only, and 2 in egg stage only. Of the species captured in larval form only, 2 have demersal eggs and therefore would not be taken in the plankton hauls. The American eel spawns in the mid- Atlantic and the northern pipefish carries the eggs until they have hatched. For the remaining 4 species, the haddock was taken only in the juvenile stage and generally dots not spawn in this area. Black sea bass larvae were captured only at station and were probably a product of offshore spawning. Bluefish and summer flounder are bclieved to have buoyant eggs, but positive identifications have never been made. The goosefish appeared in the egg stage only. One unknown egg was taken at station 2 in November. The most abundant species captured as larvae was the group classified as MyoxocephaZus spp., or sculpins. Three species of sculpin are normally found in Narragansett Bay as adults ( Myoxocephalus aeneus, M. scorpius, and M. octodecenwpinosus). It is probable that all three of these species are represented in the larval fish captured, although precise identification has not been possible. The peaks of abundance of larvae in January and March can be attributed mostly to larvae of this group. The Atlantic menhaden appeared to have a split spawning season in Narragansett Bay. Eggs and larvae were taken from May through August and again in late October, the fall spawning period being by far the most productive. In Long Island Sound, Wheatland (956) found that no Atlantic menhaden larvae were captured after surface temperature dropped to.3 C. In Narragansett Bay Atlantic menhaden larvae were captured at temperatures as low as.2 C. Postlarval Atlantic herring were taken several times during the survey. Adult finfish trawls indicated large numbers of the

4 6 SIDNEY S. HERMAN Tnr3,r;:, Species composition and actual numbers of fish eggs and larvae taken in meter and Clarke- Bumpus nets from March 957 to March 958. The figures do not include day and night replicate hazels or other extra hauls made during the survey Species Clupea harengus harengus Linnaeus Rrevoortia tyrannzcs (Latrobe) Anchoa mitchilli ( Cuvier & Valenciennes ) Anguilla rostrata ( LeSueur) Merluccius bilinearis ( Mitchill) Gadus morhua Linnaeus Melunogrammzcs aeglefinus ( Linnaeus) Urophycis spp. Enchelyopus cimbrius (Linnaeus) Paralichthys dentatt4s ( Linnaeus ) Paralichthys obzongus ( Mitchill) Pseudopleuronectes americanus ( Walbaum ) Scophthalmus aquosus (Mitchill) Trinectes maculatus (Bloch & Schncidcr) LMenidia menidia ( Linnaeus ) Gasterosteus aculeatzls Linnaeus Syngnathus fuscus Storer Poronotus triacanthus (Peck) Pomatomus saltatrix Linnaeus Centropristes striatus Linnaeus Stenotomus chrysops ( Linnaeus) Cynoscion regalis ( Bloch & Schneider) Menticirrhus saxatilis (Bloch & Schncidcr) M yoxocephalus spp. Cyclopterus lzcmpus Linnaeus Priono tus carolint4s ( Linnaeus ) Prionotus evolans ( Linnaeus ) Tautogolabrus a&ersus (Walbaum) Tautoga onitis (Linnaeus) Gobiosoma spp. Ammodytes americanus De Kay Pholis gunnellus ( Linnaeus ) Ulvaria subbifurcata (Storer) Cryptacanthodes maculatus ( Storer) Sphaeroides maculatus (Bloch & Schneider) Lophius americanus ( Valenciennes ) Unknown Common nnme.-~ ~ Atlantic Herring Atlantic Menhaden,5,256 Bay Anchovy American Eel 688 Silver Hake 6 Atlantic Cod Haddock Hakes 98 2 Fourbeard Rockling 86 Summer Flounder Fourspot Flounder Winter Flounder Windowpane Hogchoker Atlantic Silvcrsidc,362 Threcspinc Stickleback Northern Pipefish Butterfish Bluefish 2 Black Sea Bass scup Wcakfish Northern kingfish Sculpins Lumpf ish, Northern sea Robin,395 Striped sea Robin 3,488 Cunner -2,592 Tautog -2,3 Goby American sand launcc Rock Gunnel Radiated Shanny Wrymouth Northern Puffer Gooscfish 3 Larvae ; , postlarvae throughout the bay, although no larvae were captured in the plankton tows. It would seem, therefore, that Narragansett Bay is a nursery ground rather than a spawning ground for this species. Bigelow and Schroeder ( 953) state that young American eels appear in Narragansett Bay in mid or late April. Elvers were taken during the survey as early as February. Few eggs and larvae of the silver hake were taken. Adults of this species are present in great abundance during the summer in the bay. The comparatively small number of eggs and larvae collected indicated that Narragansett Bay is not a major site of spawning for this species. The silver hake eggs varied in diameter from.93 to.5 mm and contained a single oil globule which had a size range of.8 to.43 mm. This is greater than the normal range of.88 to.95 mm with an oil globule from.9 to.23 mm as described by Kuntz and Radcliffe ( 97). The hakes are difficult to separate into distinct species at an early age. Three species of adults were commonly found in the bay during the summer and fall: the white hake, Urophycis tenuis; the squirrel hake, U. chuss; and the spotted hake, U. regius. Identification of the three species in

5 FISH EGGS AND LARVAE OF NARRAGANSETT BAY 7 =T Table 2. Species composition of fish eggs with characteristics, occurrence, and abundance Approx. size Oil globule Averngc Tcmperaturc SpCCiCS range Dates abundance range (min) Number Size rnngc (No./ma) ( C) Br~oortia Anchon tyrnnnus mitchilli Merluccius bilinearis GaI:lus morhun Urophycis spp. EnIshelyopus cimbrius Pnralichthys oblongus Po-ronotus trincanthus Stenotomus chrysops Cynoscion regalis Menticirrhus saxatilis Prbnotus carolinus P&n&us evoluns Tautogolabrus hersus Tautoga onitis Lophius americanus Unknown x.9.82x lO-.5 May-August &t Nom None L June-August July-October None None November-May.36.2r.5 l-many Variable May-August l-many.o&.25 February-June lO-.5 WY l-2.o&23 JunoAugust l-2.x3-.23 May-August l-3.lo-.25 June-August Many Variable June- July Many Variable June-August Many Variable June-August None None May-September None None May-August June, April-July Trace Novcmbcr Tract. = Specks TABLE 3. Species composition of larvae with size range, occurrence, and abundance Clupea harengus harengus Brevoortia tyrannus Anchoa mitchilli Anguilla rostrata Merluccius bilinearis Ga#rlus morhun Melanogrammus aeglefinus Urophycis spp En(shelyopus cimbrius 3.36 Pal alichthys dentatus Parulichthys oblongus Pseudopleuronectes americamcs Trinectes maculatus 3.6 Menidia menidia Garterosteus aculeatis 5. Syngnathus fuscus Poronotus trincanthus Prkmotus spp Pomatomus saltatrix 3.2 Centropristes strintus Stenotomus chrysops Cylwscion regnlis Menticirrhus saxatilis Myoxocephalus spp. 5.2%.4 Cyclopterus lumpus Tautogolubrus ndspersus Tautoga onitis Gobiosomu spp Ammodytes americanus Pholis gunnellus Ulzlaria subbifurcata Cryptocanthodes muculatus 2. Sphaeroides maculatus * Bottom tcmpcraturcs. natcs March-April June-July, October-February June-November February-April July-October December-May May- June May-Novcmbcr July July-January July-Scptembcr February-June July May-July June JunoOctober July-October July-Scgtcmbcr rf:: U Junedcptcmbcr July-Scptembcr June-August January-May May June-August June-August July-August January-May Dccembcr-March May-June March June-Scptembcr Avcrago abundance (No./m ) Tcmpcrature range ( C) " O Trace

6 8 SIDNEY S. IIERMAN the hrval stage has not yet been completed; hence, the three are listed as ~rophzjcis SPP. Eggs of the fourbeard rockling were taken from February to June at stations and 2 only. Battle (929) found that 3.O C was the minimum limit for normal egg devclopment in this species. The temperature range over which fourbeard rockling eggs were taken in Narragansett Bay was from.4 to 5.2 C; the majority being caught during late winter when the temperature was below 3.O C. Only one of the 88 eggs collected had developed to the embryo stage, which suggests a temperature limitation such as noted by Battle. Since adult Iourbeard rocklings are captured rather infrequently in the bay, and since eggs were captured at only stations and 2, the eggs probably were a product of offshore spawning being carried into the bay by tidal influx. According to Hildebrand and Cable ( 93), summer flounder probably spawn in November and December, chiefly, if not wholly, at sea. Seventeen specimens ranging in size from 4.8 to 2. mm were taken from late July through late January. Identifications were based on the description by Hildebrand and Cable. The largest larva was most easily identified, having a dorsal fin ray count of 9 and a ventral fin ray count of 73. The larval fish had flattened and the right eye had partially migrated. The larvae were taken at every station but station 3. Hence, thcrc is evidence that spawning of summer flounder in Narragansett Bay commenced during the summer months and continued through the late fall and early winter. Merriman and Sclar ( 952) believed that the eggs of the butterfish which were collected in their survey in Block Island Sound were a product of offshore spawning. Wheatland (956) found that most of the eggs collected in Long Island Sound occurred at stations offshore. However, in Narragansett Bay, butt,erfish eggs and larvae were collected at each of the stations, indicating spawning activity of this species within the bay itself. Weakfish eggs and larvae were collected from June through August. An interesting feature of the spawning of this species was that spawning was initiated at stations 3 and 4 in the upper part of the bay and then progressed seaward to stations and 2. From early June to early July, weakfish eggs and larvae were taken only at stations 3 and 4. From the second week in July through August, eggs and larvae appeared only at stations and 2. Table 2 lists size range, physical characteristics, occurrence, and abundance of the eggs of the fish species found. Similar information for the various fish larvae caught is summarized in Table 3. REFERENCES BATTLE, HELI<N I Effects of extreme temperatures and salinities on the dcvclopmcnt of EncheZyov cimbrius (L. ), Contr. Canad. Biol., 5: BICJZLOW, I-. B., AND W. C. SCIUIOEDER Fishes of the Gulf of Mainc. st revision. Fish. Bull. Fish. Wildl. Serv., 53: l-577. DANNEVIG, ALP. 98. Biology of Atlantic waters of Canada. Canadian fish eggs and arvac. Canad. Fish. Exped., 94-95, EIIIIENBAUM, E. 99. Eier und Larvcn von Fischcn. Nord. Plankt., lo( 2) : HICKS, S-IXACY D The physical oceanography of Narragansett Bay. Limnol. Occanogr., 4: HII,IXZJ~RANI),!% F., ANDLOUELLA E. CABLE. 93. Devclopmcnt and lift history of fourteen telcostean fishes at Beaufort, N. C. Bull. U. S. Bur. Fish., 46: , AND Reproduction and dcvclopmcnt of whitings or kingfishes, drums, spot, croaker, and wcakfishes or sea trouts family Sciaenidea, of the Atlantic coast of the United States. Bull. U. S. Bur. Fish., 48: > AND Further notes on the development and life history of some tcleosts at Beaufort, N. C. Bull. U. S. Bur. Fish., 48: KUNTZ, ALBERT, AND LEWIS BADCLIE'FE. 97. Notes on the embryology and larval dcvelopmcnt of twclvc telcostcan fishes. Bull. U. S. Bur. Fish., 35: MEI~IXIMAN, DANIEL, AND RUTH C. SCLAR Hydrographic and biological studies of Block Island Sound. The pelagic fish eggs and larvae of Block Island Sound. Bull. Bingham Oceanogr. Coll., 3:

7 FISH EGGS AND LARVAE OF NARRAGANSETT BAY 9 PEIXMUTTER, ALFRED A biological sur- UNITED STATES FISH AND WILULIPE SEI~ICE. vey of the salt waters of Long Island, Rhode Island Landings, 957. An- Section I. An ecological survey of young fish nual Summary CFS # pp. WIIEATLAND, SARAII Oceanography of and eggs identified from tow-net collections. Long Island Sound, VII. Pelagic Suppl. 28th Ann. Rep. N. Y. Cons. Dept., Pt. fish eggs and larvae. Bull. Bingham Ocea- II, -7. nogr. Coil., 5: