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Distribution of
sculpins in the Columbia Basin
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Sculpin Xray |
Comment on Sculpins (Cottidae)
Cottidae is one of the most taxonomically complex and widespread families of freshwater fish in B.C. It can be found in lakes, streams and rivers. Cottidae is a highly adapted family of fish, with complex reproductive behaviours that include nest building and strict, male parental care. Cottids display a bewildering amount of meristic and colour variation between and within populations. To complicate things further, many sympatric species overlap in their meristic and morphometric traits and hybridize with each other. The Columbia Basin is a hotbed of sculpin diversity, both at and below the species level.
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| Cottus asper (Richardson) | |
| Cottus=an old European name asper=rough |
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Prickly Sculpins are a euryhaline species distributed
on the pacific slope of North America. It is a slow-water sculpin
preferring lake shores, pools and quiet waters in rivers (Northcote
1954). Adults are usually solitary, and do most of their foraging
for benthic invertebrates, fish eggs and small fish at night. This
species is one of the largest of the freshwater sculpins -- it can
grow to a maximum length of 150 mm, although some estuarine inhabitants
have been reported as large as 300 mm (Scott and Crossman 1973).
Spawning occurs in streams during the early spring. Males become melanistic and defend a prepared nest among boulders before females move into the breeding sites. Eggs are <1 mm, orange and usually found in clutches of 7,00-4,000 adhered to the roof of the nest (Scott and Crossman 1973). The males guard and fan the eggs as the eggs develop, and seldom leave the nest once the eggs are present. Many egg clutches in different developmental stages may be found in the nest of single male suggesting that males spawn with more than one female. A large female may lay as many as 10,000 eggs in a season (Patten 1971).
There is considerable geographic variation in reproductive behaviour (pre-spawning migration) and prickling patterns in Cottus asper, but most sculpin taxonomists recognize two forms of Prickly Sculpin; a saline-tolerant coastal variety and an interior variety (McPhail and Lindsey 1970). The geographic range of Cottus asper suggests that this species survived glaciation in more than one location in the Pacific Refuge (McAllister and Lindsey 1961). The interior form moved north postglacially through the Columbia Basin and it is currently found below barriers in the lower Columbia, lower Kootenay, Kettle and Similkameen rivers; it is, interestingly enough, ubiquitous in the Okanagan system.
The Prickly Sculpin has a high anal fin ray count (15-19) with the anal fin being distinctly longer than the head length. There is a single medial chin pore on the under surface of the lower jaw, rough prickles on the back and lateral surfaces, and a distinct black spot on the hind portion of the first dorsal fin.
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| Cottus bairdi (Girard) | |
bairdi=an
ancient name used by Rondelet, presumably after Baird |
Drawing
of Cottus bairdi from the Flathead River, B.C.
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Mottled Sculpins live in clear, cool rivers and lakes over gravel and rocky bottoms. Sexual maturity is reached in their second year and spawning usually occurs April through June (Patten 1971). Females adhere eggs to the underside of rocks in nests prepared and guarded by males.
The status of Mottled Sculpins in western Canada is poorly understood. The species is often difficult to identify because of its close relationships to other sculpin species. To complicate things further, Mottled Sculpins have been known to hybridize with the Slimy Sculpin (Cottus cognatus) (Strauss 1986; Smith 1992). Mottled Sculpins in western Canada can be divided into two groups: the western Columbia form that adheres to the description of the Columbia Sculpin (Cottus hubbsi) (Bailey and Dimik 1949), and a Rocky Mountain form following the description Cottus bairdi punctulatus (Gill). The Rocky Mountain form straddles the Continental Divide and has a limited distribution in southeastern British Columbia and southwestern Alberta (Bajkov 1927; Schultz 1941; McPhail 1994).
Populations of Mottled Sculpin in the Flathead system have been consistently tagged as unique, and many accounts have suggested that these fish resemble Shorthead Sculpins (Cottus confusus) (McAllister and Lindsey 1961; Peden et al. 1989). Evidence that is more recent suggests that the isolated Flathead populations are in fact Mottled Sculpins (Cottus bairdi punctulatus) that share characters with the Slimy Sculpin (Cottus cognatus) (Troffe 1999b).
Mottled Sculpins are present in the Kettle, lower Kootenay below Bonnington Dam and the Lower Columbia rivers, below barriers in the Similkameen, and present in a unique form in the Flathead system.
Mottled Sculpins are a variable species that generally have papillae on the top of the head, well-developed palatine teeth, and an anal fin that is pigmented with fine, black spots. Columbia Basin specimens exhibit prickles behind the pectoral fin and have a complete lateral line. Flathead River and western Alberta populations lack the prickles behind the pectoral fin and have an incomplete lateral line.
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| Cottus cognatus (Richardson) | |
| Cottus=an old European name cognatus=related to the European species, C. gobio |
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The Slimy Sculpin is widespread in North America
and eastern Siberia, and this polymorphic species is thought to
be represented by at least two forms in British Columbia -- a northern
and a southern form (McPhail and Lindsey 1970). The Slimy Sculpins
of the Columbia and upper Fraser basins appear intermediate between
the two forms. The Columbia Basin may have been a mixing zone for
this species post-glacially, or some Slimy Sculpin populations survived
glaciation west of the Continental Divide in Washington or Idaho
State (McAllister and Lindsey 1961).
The Slimy Sculpin rarely exceeds 100 mm in length. It is typically found in cool running water with rocky or sandy bottoms along the edges of rivers, but may be present near lake inlets. Spawning occurs during the spring when ripe males select a nesting site under rocks and large cobble. Courted females lay adhesive eggs on the roof of the nest, and males guards the eggs and hatching larvae until the larvae begin feeding. Nests often contain egg clutches in different developmental stages suggesting that multiple females may spawn with a single male. A large female can lay as many as 1,400 eggs (Scott and Crossman 1973).
Insect larvae and nymphs, including mayflies, caddisflies and dragonflies, make up the majority of the Slimy Sculpin's diet; although larger fish have been known to have fish larvae and salmonid eggs in their guts. Slimy Sculpins are a common prey item of Burbot and of trout species, and have been used as angling bait (McPhail and Lindsey 1970).
Slimy Sculpins are common above and below barriers throughout the Oakanagan, upper Columbia and Kootenay systems. They are absent above waterfalls in the Similkameen and are rarely found in the tributaries of the lower Columbia. This cottid species is most abundant in cooler headwater reaches, especially in the Flathead Valley (Hughes and Peden 1984).
The Slimy Sculpin is, as the common name suggests, slimy to the touch. Palatine teeth are absent and so are head papillae. The lateral line is incomplete and usually terminates near under the middle of the second dorsal fin. The anal fin usually has 10-13 rays. The pelvic fins have three rays, but, when a fourth is present it is usually only three-quarters the length of the longest rays (Hughes and Peden 1984). There is some evidence that Mottled Sculpins (Cottus bairdi) and Slimy Sculpins share characters in areas where they overlap in the Flathead system.
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| Cottus rhotheus (Smith) | |
| Cottus=an old European name rhotheus=rushing of the torrent |
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The Torrent Sculpin is a unique western North
American species endemic to British Columbia, Washington, Oregon,
Idaho and portions of northwestern Montana (Scott and Crossman 1973).
Torrent Sculpins are most common in swift streams, although they
may be found in lakes along beach margins. Stream dwellers live
in fast waters with a gravel and cobble substrate and are often
one of the larger cottid species present. This species is phenotypically
and behaviourly variable throughout its range, and is often observed
in sympatry with the Mottled Sculpin (Cottus bairdi). Many
populations isolated above waterfalls along the tributaries of the
lower Columbia River exhibit differences in prickle patterns and
spawning activities (McPhail and Carveth 1994; Troffe pers. obs.).
Young Torrent Sculpins forage for plaktonic crustaceans and move to an aquatic insect larvae diet as they grow. Adults 70 mm or longer forage almost exclusively for juvenile cyprinids and other fish (Northcote 1954). Torrent Sculpins are one of the longer-lived cottid species, and can live up to seven years and reach a maximum size of about 155 mm.
Spawning occurs from May to July in animals two years and older. The fecundity of females is quite low, with large females usually producing less than 500 eggs a season (Patten 1971). As the spawning season approaches, territorial males turn melanistic and the tip of the first dorsal fin becomes bright orange.
Torrent Sculpins are heavily prickled especially on the wide head, dorsal and lateral surfaces. The lateral surface is usually marked with two distinct forward-sloping stripes that originate under the second dorsal fin and the chin is heavily mottled.
Torrent Sculpins are absent from the Flathead system, but found throughout the Columbia Basin except areas above barriers in the Kettle, Okanagan and Similkameen systems.
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| Cottus confusus (Bailey and Bond) | |
| Cottus=an
old European name confusus=clouded, referring to the irregular body pigment |
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The Shorthead Sculpin is the most confusing and
elusive freshwater sculpin species in British Columbia. The taxonomy
and distribution of this species has been debated since the species
was first proposed by Bailey and Bond in 1963. Since its inception,
this species has been used as a catch-all for sculpins from the
Columbia Basin that exhibit intermediate characteristics between
the Slimy Sculpin (Cottus cognatus) and the Mottled Sculpin
(Cottus bairdi) (Peden et al. 1989). This Columbia
Basin endemic species is often found together with other cottid
species, and it is thought to be restricted to northeastern Oregon,
Idaho, eastern Washington and southeastern B.C.
The Shorthead Sculpin is usually found in fast riffles in colder streams with gravel and cobble substrates, but may be found along the edge waters of larger rivers. This species seems to prefer cooler upstream habitats, although populations in British Columbia have been found in many stream reaches of the lower Columbia (Peden et al. 1989).
Shorthead Sculpins mature at two to three years of age, and spawn during the early spring in rocks and cobble of larger streams. The males become melanistic and emaciated during the breeding season and defend the nest. This species rarely exceeds 100 mm in length, and mature females have a mean fecundity of 326 orange-yellow eggs -- making them one of the least fecund freshwater sculpin species (Cannings and Ptolemy 1998; Patten 1971).
The Shorthead Sculpin is very difficult to identify, and it generally resembles the Mottled Sculpin (Cottus bairdi) and the Slimy Sculpin (Cottus confusus). The lateral line is generally complete and ends in an axial scar near the caudal peduncle. The presence (although they may be weak) of palatine teeth and two post-maxillary pores, and two to three preoppercular spines can separate C. confusus from C. cognatus. Head papillae are generally absent, and the pigmentation of the anal fin is dusky and lacks clearly defined spots.
In Canada the Shorthead Sculpin is restricted to the Kettle river below Cascade Falls, the tributaries of the lower Columbia and portions of the Slocan River. Earlier reports of nominal Shorthead Sculpins in the Flathead River drainage should be treated as suspect, as they appear more closely allied with the Mottled Sculpin (Cottus bairdi) (Troffe 1999b).
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