Species Description: The pinfish, Lagodon rhomboides, is a common inshore fish belonging to the family Sparidae, the porgies. The body is compressed and oval, olivaceous above, bluish-silver along the sides with thin yellow stripes running longitudinally. A dark shoulder spot occurs near the anterior origin of the lateral line. Six broad diffuse vertical dark bars occur along each side of the body, and these are most prominent in younger individuals and in individuals experiencing stress. The anal fin and the forked caudal fin are both yellowish with broad light blue margins (Randall et al 1978, Muncy 1984).
The mouth is comparatively small, with the maxilla reaching only to below the anterior margin of the eye. Upper and lower jaws each have eight broad, deeply notched incisor-like anterior teeth, and 2.5 lateral rows of molar-like teeth (Randall et al 1978).
A single small, forward-projecting spine precedes the 12 dorsal spines. This pin-like spine gives the species its common name. Hoese and Moore (1977) report the ray and scale count for L. rhomboides as: Dorsal spines XII, soft rays 11; anal spines III, rays 11; scales 65-70 along the lateral line.
Potentially Misidentified Species: The genus Lagodon is monotypic, but pinfish may still be confused with other co-occurring fish in the IRL. The longitudinal yellow lines confer some resemblance to various species of grunts, although head, mouth and teeth morphologies are substantially different so that most confusion is avoided. Particularly as juveniles, pinfish may also be mistaken for sheepshead (Archosargus probatocephalus), who are also members of the porgy family. The dark vertical bars of the sheepshead are more prominent and more persistent than those of pinfish.
Regional Occurrence: Lagodon rhomboidesis found on the eastern coast of the United States from New England south to Florida, Bermuda, the northern Gulf of Mexico, the northern coast of Cuba, and the Yucatan (Hoese and Moore 1977, Burgess 1980, Froese and Pauly 2008). The species appears to be absent from the Bahamas and the rest of the Antilles (Smith 1997). Froese and Pauly (2008) list L. rhomboidesas a subtropical species occurring from 43° to 20° north latitude.
The species has historically been abundant from Virginia southward (Hildebrand and Cable 1938). Muncy (1984) notes pinfish are less abundant north of Maryland, and juveniles collected from Delaware estuaries appear to have migrated there from spawning grounds to the south (Wang and Kernehan 1979).
IRL Distribution: Pinfish are distributed throughout the estuarine and nearshore waters of Florida and are known to be present in all Florida coastal counties. They occur throughout the IRL system.
Age, Size, Lifespan: Based on whole otolith analysis, Nelson (2002) recorded pinfish as old as 7 years, although the vast majority of individuals do not live nearly that long. The author estimated a high instantaneous natural mortality rate of 0.78/year and a total instantaneous natural mortality rate of 0.90/year. Earlier, Hellier (1962) had reported no more than 2% of age 0 pinfish in Laguna Madre, TX, survived from hatching to reach age 1 in the following February.
Young-of-the-year Lagodon rhomboides exhibit rapid growth; Nelson (1998) reports instantaneous growth rates of 0.10-0.25 cm/month for such individuals.
Hansen (1970) reports an average standard length (SL) of 12.7 cm (5 inches) for age-2 pinfish. Randall and Vergara (1978) report a maximum total length (TL) as 40 cm. The maximum published weight for the species is 1,510 g (IGFA 2001).
Abundance: Pinfish can be extremely abundant in certain areas and at certain times of the year. In years of high recruitment, young-of-the-year pinfish are likely to be the numerical dominant fish species in the IRL (Stoner 1980). Abundance of mature animals can also be considerable. Springer (1957) reported multiple schools of more than 1,000 adult pinfish each off the Mississippi coast. All females sampled from these schools were ripe and these schools may have been spawning.
In some areas pinfish become seasonally so abundant that their foraging activities are capable of altering the composition of estuarine epifaunal seagrass communities (Stoner 1982).
Reproduction: Pinfish mature after one or (usually) two years, when they have reached a standard length (SL) of around 80-100 mm (Hansen 1970, Johnson 1978). Average standard length at 50% maturity was estimated to be 13.2 cm (Hansen 1970).
Darcy (1985) reports that mature pinfish migrate to offshore waters in the late fall and spawn offshore from late fall through early spring. Hansen (1970) suggested that most pinfish mature during the offshore spawning migration or at offshore spawning sites.
Hansen (1970) reported that adult female pinfish between 111 and 152 mm SL contained an average of 21,600 eggs. Caldwell (1957) estimated that a 157-mm long female collected from Florida in late November contained approximately 90,000 eggs.
Pinfish eggs are roughly 1 mm in diameter, usually with a single oil globule and a very narrow perivitelline space. Laboratory studies by Schimmel (1977) indicated that fertile eggs were semibuoyant, while non-viable eggs sank to the bottoms of finger bowls.
Embryology: Schimmel (1977) described the embryology and larval life history of pinfish. Larvae hatched out after approximately 48 hours at 18°C and averaged 2.3 mm in length. The yolk sac, visible 24 hours after hatching, is completely absorbed once larvae reached a size of 2.7 mm. At 96 hours, mouths begin to develop in the 3 mm-long larvae. Soft rays begin to form at 5-7 mm total length, and spines begin to differentiate at 8-10 mm TL. The caudal fin undergoes several morphological changes to finally become concave at 14 mm TL. Teeth are formed at 10 mm TL, and scale formation begins at 15 mm TL (Johnson 1978).
Field studies indicate that larval pinfish begin moving into estuarine waters at around 11 mm TL (Johnson 1978). Reid (1954) collected larvae ranging between 11 mm and 18 mm in estuarine waters near Cedar Key, Florida, from late November through early January. A study by Thayer et al. (1983) revealed greater nighttime pinfish larval abundance in surface waters, compared to samples collected during the day. Wang and Kernehan (1979) report that juveniles continue to migrate into the estuaries through spring and into the summer.
Temperature: Pinfish tolerate temperature fluctuations typical of shallow subtropical estuaries, roughly between 10°C and 35°C. They do, however, exhibit behavioral responses to thermal extremes. When surface temperatures in shallow estuaries exceed 32°C, for example, most juvenile pinfish move into the cooler deep water of adjacent manmade channels (Cameron 1969). In contrast, this author noted that larger pinfish moved out of shallow flats but some juveniles remained inshore when temperatures dropped below 10°C.
Peters et al. (1973) note that feeding stopped at temperatures above 35°C and below 6°C. Lewis and Mann (1971) report that pinfish ceased feeding when water temperature reached 36°C and succumbed after 24 hours at 36°C.
Snelson and Bradley (1979) report a mortality event in which large numbers of pinfish (70-150 mm) were killed when winter surface water temperatures fell to 4°C.
Salinity: Pinfish are considered euryhaline. They spend most of their time in the estuaries, but they spawn in fully marine coastal waters and they are also frequently encountered in low-salinity environments (FWRI 2006). The literature contains several accounts of juvenile pinfish being collected from fresh water (Randall et al. 1978, Johnson 1978, Burgess 1980). Hellier (1962) reports pinfish occurring in hypersaline waters as high as 75 ppt.
Studies examining the influence of salinities ranging from 0 to 60 ppt on juvenile pinfish have found that the highest rates of growth and survival occur at estuarine salinities of 15 to 30 ppt (Shervette et al. 2007).
Dissolved Oxygen: Cameron (1970) reports that the oxygen-carrying capacity of pinfish blood increases as in response to decreased environmental oxygen, increased activity levels, and increased salinity, all of which increase respiratory demand.
Pollutants: Bioassays have indicated that pinfish are highly susceptible to the pesticide Antimycin A, PCB's, and the insecticide mirex (Finucane 1969, Hansen et al. 1971, Tagatz 1976). Wohlschlag and Cameron (1967) reported that petrochemical wastes depressed pinfish respiration and caused up to 10% mortality in polluted waters near Corpus Christi, TX.
Trophic Mode: Juvenile and subadult pinfish are voracious and efficient predators who feed primarily on small crustaceans such as shrimp, mysids, and amphipods (Carr and Adams 1972, Stoner 1979, Nelson 1979). Other dietary items include fish eggs, insect larvae, decapod crabs, bivalves and polychaetes (FWRI 2006). Larval pinfish feed primarily on calanoid copepods (Stoner 1979).
As they mature, the species exhibits an ontogenetic dietary shift, with older animals consuming increasing amounts of plant material in addition to animal prey (Stoner 1980). Luczkovich et al. (1995) notes that this shift accompanies a physical change in the shape of the incisors to a flat-topped morphology and a change in foraging technique from suctorial and ram feeding to biting.
The high seasonal abundance of pinfish in Florida inshore waters is believed capable of shaping the structure of small phytal invertebrate communities (Stoner 1980). Intense pinfish predation on several species of amphipods in the spring and summer months is likely limiting the population sizes of these prey species (Nelson 1979). Consumption of plant and detrital material by adult pinfish also affects the way in which these refractory organic materials are cycled through the estuary (Adams 1976).
Competitors: Given the seasonal numerical dominance of Lagodon rhomboides within the estuaries, the most severe competition is likely to be intraspecific in nature, with pinfish of the same size class competing with one another for food resources.
Predators: While important as consumers of a variety of small invertebrate prey items, pinfish are equally important as a prey resource for several larger fish species, including gars, ladyfish, spotted seatrout, redfish, bighead sea robin, southern and Gulf flounders, and others (Darcy 1985, FWRI 2006). Pinfish are also a common prey species of bottlenose dolphin (Muncy 1984).
Several species of fishes and wading birds likely prey on L. rhomboides. Especially as juveniles, pinfish seek refuge from predators in sheltered areas like seagrass beds (e.g. Harter & Heck, Jr. 2006).
Parasites: The isopod Lironeca ovalis and the haematozoan Haemogreyarina bigemina have been reported as important parasites of Lagodon rhomboides (Muncy 1984). Parasite infestation was reported as the most prevalent gross external abnormality in Florida Gulf coast pinfish, whereas ulcers/lesions were most common on the Atlantic coast (FWRI 2006).
Habitats: Lagodon rhomboides is an abundant demersal estuarine species typically found in vegetated benthic habitats such as seagrass beds. The species is also commonly encountered over bare sand, rock reefs, in mangrove habitats, and off of inlet jetties (Randall et al. 1978, Robbins and Ray 1986). Juveniles 20-80 mm are most abundant in shallow, vegetated habitats.
Activity Time: Caldwell (1957) reported that pinfish were free-swimming during the day, while Hastings et al. (1976) suggested they prefer to remain under cover at night. Trawl catches from Whitewater Bay, FL, contained the greatest abundance of pinfish when trawls were conducted at night when tidal currents were minimal and where aquatic vegetation was abundant (Clark 1974).
Stoner (1979) reports that juveniles will leave the protection of seagrass habitats to venture into adjacent bare sand patches.
Economic Importance: Minor commercial fisheries centered on Lagodon rhomboides exist, including a Florida baitfish fishery. The species is also expoited by anglers as a minor sportfish. Most landings of pinfish in Florida are made by the recreational fishery; in 2005, approximately 96% of the 1,424,302 pounds of pinfish landed in Florida were landed by recreational anglers (FWRI 2006). 85% of this total was landed on the Gulf Coast.
Randall at el. (1978) suggested pinfish as a potential source of fish meal, and Hildebrand and cable (1938) noted that the species yielded a high grade of oil. There appears to be little or no present-day use of the species for these purposes in Florida.
Pinfish have also been used extensively as test organisms, primarily in pesticide toxicity assays (Finucane 1969, Muncy 1984).
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