Kelp

Spotting kelp-dwelling fish requires slow, deliberate observation within kelp canopies (*Macrocystis pyrifera*), surfgrass, and understory algae. Giant kelpfish and kelp rockfish blend seamlessly into brown and green foliage; carefully inspect individual kelp stipes and blades where kelp rockfish rest during the day. Approach slowly to observe territorial giant kelpfish males, which defend soft algal nests against intruders from up to 3 metres away.

Night diving presents excellent opportunities to view kelp rockfish actively hunting crustaceans, gastropods, and small fish, as well as female rockfish giving birth to viviparous broods after dark. Divers should maintain precise neutral buoyancy to avoid disturbing delicate kelp fronds and algal nests hidden within understory vegetation. Avoid touching kelp perch when they act as cleaner fish within the canopy, and look for kelp greenlings resting near rocky drop-offs and adjacent sand substrates.

Kelp-associated fish can be observed year-round across California and Baja California, but key biological events occur seasonally. Kelp bass form prominent spawning aggregations of 50 to 200 individuals from late spring through early autumn, with peak activity during summer (June, July, and August). Spawning peaks around full moon cycles between 32 minutes before and 120 minutes after sunset.

Giant kelpfish spawn year-round, but spawning peaks during spring. During this period, male giant kelpfish actively build concealed nests of soft red or brown algae and exhibit bright green or yellow nuptial coloration. Kelp rockfish spawning begins in February in northern California and shifts to March further south. In northern waters such as British Columbia and Alaska, diving for kelp greenling and kelp perch is most favorable during summer when underwater vegetation cover is at its peak.

These species inhabit the eastern Pacific Ocean, distributed from the Aleutian Islands in Alaska south to Baja California, Mexico. Their depth range extends from shallow intertidal zones down to 61 metres, with most species concentrated between the surface and 30 metres depth.

Primary habitats consist of nearshore rocky reefs and dense giant kelp forests dominated by *Macrocystis pyrifera*, along with understory brown algae such as *Pterygophora californica*, *Cystoseira osmundacea*, and *Desmarestia* species. Giant kelpfish also utilize surfgrass and eelgrass beds as alternative habitats, with juveniles occupying upper macroalgae sections and older individuals gathering near the plant bases. Kelp greenlings inhabit rocky nearshore areas, kelp beds, and sand bottoms, while kelp rockfish are also known to colonize artificial habitats such as oil rigs.

Dietary habits vary by species and time of day. The giant kelpfish is a carnivorous bottom-feeder equipped with a terminal mouth suited for ambush predation; it preys on small crustaceans, mollusks, and small fishes, while its planktonic larvae feed on single-celled algae and mollusk larvae. Kelp greenlings feed on crustaceans, polychaete worms, brittle stars, mollusks, and small fishes.

Kelp rockfish are primarily nocturnal hunters, feeding at night on isopods (*Pentidotea resecata*), cephalopods, gastropods, and small fish such as juvenile blue rockfish and plainfin midshipmen. Kelp bass utilize various micro-habitats within the kelp forest canopy and rocky reefs to prey on smaller organisms. Kelp perch act as cleaner fish, picking parasites off other marine species within kelp beds.