Redbreast sunfish (Lepomis auritus) COSEWIC assessment and status report: chapter 3

Species Information

Name and classification

Class

Actinopterygii

Order

Perciformes

Family

Centrarchidae

Genus

Lepomis

Species:

Lepomis auritus (Linnaeus, 1758)

Common name

English:

redbreast sunfish (Nelson et al. 2004)

French:

crapet rouge (Scott and Crossman, 1998)

Other:

Yellowbelly sunfish, longear sunfish, redbreast bream

Morphological description

The redbreast sunfish (Figure 1) is a relatively small fish with a deep, laterally compressed body. Scott and Crossman (1998) report total lengths (TL) of 130 to 180 mm.

Figure 1. Adult, male Redbreast sunfish, Lepomis auritus, from Oromocto Lake, NB, 2005. Canadian Rivers Institute (CRI) - Freshwater Fishes of New Brunswick.

Figure 1. Adult, male Redbreast sunfish, Lepomis auritus, from Oromocto Lake, NB, 2005. www.unb.ca/cri - Freshwater Fishes of New Brunswick.

The colour can range from a dark olive to a brown/bronze coloured back, becoming lighter down the sides to a yellow or red belly, from which is derived the common name. The sides commonly have reddish spots and bluish streaks (McClane 1978; Scott and Crossman 1998; Schultz 2004). The redbreast sunfish has two connected dorsal fins: the first has spines, and the second is soft rayed. The pectoral fins are high on the sides, short, and rounded (Schultz 2004; Scott and Crossman 1998).It is distinguished from other sunfish by its opercular flap (gill cover), which is long and slender (no wider than its eye) and lacks a coloured border. This is characteristic of adults, but fish under 5 cm in length (generally young of year or yearlings, see Figure 6) are often not distinguishable from pumpkinseed sunfish, Lepomis gibbosus, of similar size(Scott and Crossman 1998; Schultz 2004).

Genetic description

The genetic population structure of the redbreast sunfish in Canada is unknown.

Designatable units

Canadian populations are restricted to southwestern New Brunswick. The population structure is unknown, and there is no evidence supporting the identification of designatable units below the species level.

Eligibility

Gilbert (USGS unpubl. report) suggested that the natural range of the species is largely restricted to the Atlantic coast from the Penobscot River in Maine south to peninsular Florida, and considered it to have been introduced to New Brunswick. Nelson et al. (2004) also alluded to the possibility that the species is not native to New Brunswick without providing further discussion or documentation. Gilbert (USGS unpubl. report) based his reasoning for non-native status in New Brunswick on three arguments: 1) that Kendall (1914) reported that the northern limit of the range was the Penobscot, Kennebec, and Androscoggin river drainages of Maine; 2) there is confusion over identity of the sunfish in the Cox (1896) report; and, 3) the species has not been found in Nova Scotia (Livingstone 1953) – it might be expected to be in Nova Scotia if it was native to New Brunswick.

However, Gilbert’s speculation that Kendall’s (1914) report of the northern limit of the range as Maine is erroneous. Kendall (1914) clearly stated the range as “New Brunswick to Florida and Louisiana, abundant east of the Allegheny Mountains” (Kendall 1915: 50). Scott and Crossman (1959; 1998) did indicate that Cox’s (1896) inclusion of the species in New Brunswick may have been erroneously based on the more common Lepomis gibbosus, and accepted the first bona fide record as that of a specimen taken in the Canaan River in 1948, without specifying that this was the northern limit of the native range, or that the species had been introduced into New Brunswick. Houston (1990) apparently accepted it as native to the fauna of New Brunswick; however, the question was raised during assessment of the species by COSEWIC at its April 1989 Species Assessment Meeting, and the Committee at that time accepted it as native to New Brunswick (R. Campbell, Co-chair, COSEWIC Freshwater Fishes Species Specialist Subcommittee, Ottawa, ON, personal communication). Finally, there is no reason to expect the species to be found in Nova Scotia simply because it occurs in New Brunswick.

The question of the origin of peripheral species is not easily resolved. In the east, there were very few specific collection efforts in the early decades of the 20th century to verify the accuracy of the early records of researchers such as Cox (1896) or Kendall (1914). It is not surprising that it was not until 1948 (Scott and Crossman 1959, 1998) that a verified record for the species was reported for New Brunswick. Adding to the confusion is the natural rarity of the species, lack of interest and possible confusion with the more common pumpkinseed (Houston 1990). The answer to the question of whether the Canadian population is native or introduced hinges on its native distribution in adjacent American states, especially Maine. Schmidt (1986) reviewed the zoogeography of northern Appalachian freshwater fishes and treated this species as native north to the St, John River drainage, which is in line with Kendall’s (1914) report. The distribution makes zoogeographic sense based on the presence of a northeastern coastal refugium (Schmidt 1986), which explains the presence in the area of a number of species (of fishes) that cannot otherwise be readily explained as a result of dispersal (D. E. McPhail, University of British Columbia, Vancouver B.C., personal communication).

In conclusion, this is a recognized species (Nelson et al. 2004), and there is no evidence to suggest that the species was introduced into New Brunswick where reproducing populations are known from at least 15 widely separated locations.

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