The Tidewater Goby is an endangered fish that inhabits Devereux Slough. Tidewater gobies were rediscovered in the Slough in the winter of 2005, after being absent from this estuary for approximately three decades. The decline of Tidewater Gobies has been primarily attributed to the loss of suitable wetland habitat resulting from coastal developments, along with freshwater diversions from coastal streams and predation or competition from introduced species.
The Devereux Slough Monitoring Program has been regularly monitoring goby populations to give researchers a better understanding of the seasonal fluctuation in goby populations and their relative abundance.
The tidewater goby rarely exceeds 2 inches in length and has large pectoral fins. The first and second dorsal fins are closely spaced, and the first dorsal fin has a clear/yellow tip. These gobies form loose aggregations from a few to hundreds of individuals in shallow water with very low salinity (generally less than 10 parts per thousand). Nesting occurs in the spring, when males guard the eggs, which line the walls of a burrow in coarse sand.
The longjaw mudsucker, up to 8 inches long, has a very large mouth extending to the base of the pectoral fins. Its color ranges from yellow to nearly black, but usually light brown, with some irregular black splotches. It inhabits muddy areas in tidal flats, bays, and coastal sloughs from Northern California to the Gulf of California. They spawn from January to July, when males build nests for several thousand club-shaped eggs.
These fish are air breathers, allowing them to live out of water for 6-8 days if kept moist.
The California killifish is blue green and purple with a faint stripe and short dark bars on the side. Breeding males are dark brown to blackish. It is very small with a rounded caudal fin (tail). The killifish r anges from Morro Bay to Baja California in bays and nearshore salt marshes. It feeds on insects and insect larvae, so it has an upward pointing mouth for surface feeding. The Killifish has been subject of several research projects at Coal Oil Point Reserve because their behavior is changed when they are parasitized by trematodes. The trematodes makes the Killifish flash on the surface and become more vulnerable to be eaten by birds. The parasite can then complete its life cycle in the bird (Lafferty.XX)
The top smelt is green with a bright silver side stripe on the side. It can reach sizes up to 14.5 inches and ages of 6-9 years. It has two dorsal fins, and the first one has 5-9 spines. Its mouth is small and at the tip of the snout, with forked teeth. Top smelt spawn from April through October, when females may deposit eggs more than once during the summer season. Eggs have elongated filaments and are deposited in vegetated areas, and hatching may occur over a wide range of salinities. Larvae are abundant in tidal basins, and they swim in small schools near the surface off the estuary. They are found from Vancouver to Southern California. The Top Smelt is a major resource for fish eating birds.
This non-native fish was introduced to California as early as 1922, and is an effective control of mosquito populations by eating the larvae as they hatch (100-200+ in one day!). They give live birth, and therefore do not need specialized habitat for breeding, making them adaptable to many different environmental conditions. They live for 1-3 years and reach sizes of 2-3 inches, tolerating a wide range of salinities and temperatures (33-100 oF).
While mosquitofish can be important parts of mosquito control programs, they can also have negative impacts on native species. Incredibly predaceous, they also eat tadpoles, insect and amphibian larvae, and aquatic insects, and other small fish. They also compete with native minnows for food.
The arrow goby is common in estuaries, lagoons, and tidal sloughs from Canada to Baja California and it is sometimes confused with the Tide water goby. It lives on sandy and muddy substrates in fresh or salt water, and will build a burrow during low tides to await the higher tide.
The arrow goby reaches 2.5 inches in length. It has a large mouth and a long anal fin, colored tan, gray or olive with black speckles, possibly with white spots on side and head. Males usually have a black stripe on the anal fin.
The striped mullet is one of the larges fish in the Devereux Slough, reaching 1.5 feet in length and 3 pounds in weight! It is blue-gray or green, with silver on the sides and white on the bottom, and black horizontal stripes. It has a small, upturned mouth and a fleshy translucent area around the eye. It inhabits tidal estuaries and coasts worldwide.
The sculpin is easily distinguishable by their large flat head, long jaw with protruding teeth, and gill covers that end in antler-like projections. Its uppermost cheek spine is broad and flat with three branches at the tip. Staghorn Sculpins can reach 5-6 inches and are gray-olive on their back, yellow on the sides, and white on the underside. The fins have dark bars, except for the 1st dorsal fin, which has a dark splotch near the back.
Although Scuplins can tolerate a wide range of salinities, they spend most of their lives in salty water. Juveniles are found in the Devereux slough, where they feed on invertebrates, small fish, and insect larvae. They feed mostly at night and spawn in January to February.