John Stephens

• PhD
• Vantuna Research Group

We analyzed fish data from 2332 trawls collected from depths between 55 and 1280 m off the coast of California. For the 732 species known from California, including 283 species (~39% of the California ichthyofauna) in this study, very few were contained by the faunal break at Point Conception, with 21% limited from the south and only 4% from the no...

Many nearshore rockfish species have small homerange sizes and therefore may be affected by heavier localized fishing in nearport areas. For this study we examined longterm trends in rockfish and lingcod landings from the commercial passenger fishing vessel (CPFV) fishery along the south central coast (SCC) of California using data from two sources...

Rockfishes (Sebastes spp.) have historically comprised a large proportion of catches in the nearshore recreational fishery in California, but declining populations of some species have led to increasingly restrictive management of the resource. This report summarizes new and existing data on rockfishes of the south central coast of California. In 2...

Do artificial reefs serve as productive marine fish habitats (sources) or do fish assemblages of such reefs contribute little to the gene pool of succeeding generations (sinks)? Using data from a 24-year study of the breakwater at King Harbor (California, USA), annual densities of reef fish larvae were compared with densities observed elsewhere in...

The abundance of two embiotocids (Embiotoca jacksoni and Rhacochilus vacca) was surveyed continually from 1974 to 1998 on the breakwaters comprising King Harbor in Redondo Beach, California, and a nearby natural rocky-reef as a reference. Embiotocids provide an interesting model for reef-fish production because they are viviparous and their entire...

Habitat valuation is an essential tool for tracking changes in habitat quality and in adjudicating environmental mitigation. All current methods for estimating habitat values of coastal marine sites rely heavily on the opinion of experts or on data variables that can readily be manipulated to influence the outcome. As a result, unbiased, quantitati...

Substantial changes have occurred in assemblages of nearshore reef fishes in the Southern California Bight during the past two decades. At two sites off Los Angeles, California, species richness of reef fishes fell 15-25%, and composition shifted from dominance by northern to southern species. Additionally, by 1993, 95% of the fish species had decl...

Kelp bass, Paralabrax clathratus, and barred sand bass, P. nebulifer, are major components of the nearshore marine environment in the southern California Bight. Both species are also very important parts of the marine recreational fishery. Surveys at King Harbor, Redondo Beach, California, have shown that kelp bass primarily recruit between August...

In contrast to most artificial reefs which are placed at relatively deep depths so as not to interfere with shipping, rocky breakwaters provide important habitat in the intertidal-shallow subtidal zone. This zone is especially preferred for recruitment by many rocky shore fishes. The breakwaters of King Harbor, Redondo Beach, California enhance thi...

Since 1974, the Vantuna Research Group has been studying the fish assemblage on and adjacent to the artificial breakwaters at King Harbor, California. Sampling includes diver transects, ichthyoplankton tows, and air lift/quinaldene samples of settling recruits. During this 18-year study, two natural environmental events, the El Niños of 1977-1979,...

SYNOPSIS. For reef fish in temperate marine regions, such components of local assemblage diversity (i.e., within a reef) as species richness, total fish density, and rank order of abundance can remain relatively constantthrough time. Long-term data (17 years) for assemblages on 2 reefs in Southern California revealed that, despite high turnover in...

Considers various processes and factors, together with the spatial and temporal scales over which they operate, that can influence local diversity (and its estimation) of reef fishes. Mechanisms that can "buffer' local diversity of reef fishes include dispersal of young that inter-connects subpopulations, high "inertia' in relative abundance and po...

Fishes, because of their relatively large size and ease of identification, have long been used as indicators of environmental change (Hubbs 1948, Täning 1953, Radovich 1961, Cushing 1982). Further, the mobility and sensory perception of many species allow them to avoid environmental perturbations, and thus they can show a rapid response to environm...

The study examined the efficiency of fish diversion and survivorship of diverted fishes in the San Onofre Nuclear Generating Station Fish Return System in 1984 and 1985. Fishes were diverted back to the ocean with high frequency, particularly in 1984. Most species were diverted at rates of 80% or more. Over 90% of the most abundant species, Engraul...

A series of bimonthly trawls was made at stations off three areas (Ormond Beach, Redondo Beach, and San Onofre) in the Southern California Bight. Three depths (6.1, 12.2, and 18.3 m) were sampled from 1982 to 1984. At all three areas, queenfish (Seriphus politus), white croaker (Genyonemus linearus), and northern anchovy (Engraulis mordax) dominate...

Behavioral responses to chemically dechlorinated seawater were studied using two species of marine fish associated with power plant discharge areas off Southern California. Opaleye (Girella nigricans) neither avoided nor were attracted to chlorinated seawater containing 0·1 mg/liter total residual oxidants (TRO) which had been dechlorinated using e...

We conducted underwater fish assemblage surveys, benthic quinaldine sampling, and ichthyoplankton collections over high and low relief reefs at Palos Verdes Point, California from 1974 through 1981. Seventy-three species (adults and larvae) were collected or observed at Palos Verdes. Of the 24 most abundant species, 8 showed significant abundance t...

The preferred temperatures of juveniles of four embiotocid species were determined in a laboratory gradient apparatus. Juvenile Embiotoca jacksoni and Micrometrus minimus preferred warmer water than adults, although adults and juveniles of both species coincided in field occurrence. Hypsurus caryi adults and juveniles preferred equivalent temperatu...

Dwarf perch Micrometrus minimus, shiner perch Cymatogaster aggregata, blacksmith Chromis punctipinnis, black perch Embiotoca jacksoni, rainbow seaperch Hypsurus caryi, and calico rockfish Sebastes dalli were collected in a vertical thermal gradient at the breakwater of King Harbor, Redondo Beach, California. Fish were acclimated at the field temper...

Subtidal studies of fish stocks conducted along a rock breakwater in Southern California reveal a rich and diverse fauna with elements from cool and warm temperate regions. More than 100 species have been observed with half of these resident. Only a single large, permanently territorial species occurs on the reef though many small, often cryptic sp...

The diets of 5 species of embiotocids (Rhacochilus vacca, Embiotoca jacksoni, Hypsurus caryi ryi, Phanerodon furcatus and Micrometrus minimus) from King Harbor, Redondo Beach, California, USA, are examined by means of a dietary survey, field feeding observations and bomb calorimetry of prey items. Each species is shown to have statistically differe...

Three species of the blenniid genus Hypsoblennius, H. gilberti, jenkinsi, and gentilis, coexist in the shallow waters of the San Diegan Warm Temperate Region. Extensive field and laboratory studies were carried out to determine the degree of ecological differentiation present in these species. The dominant species, H. gilberti and H. jenkinsi show...

We describe Cottoclinus new genus, type species C. canops novum, from two speci-mens from Española Island, Galápagos Islands. The new genus is assigned to the labrisomid tribe Mnierpini Hubbs. The tribe is redefined and considered sister to the Labrisomini. It is united by nine synapomorphies: 1) body elongate to moderately elongate (depth 13%–22%...

Recruitment of pelagic marine larvae into a population is a critical process in nearshore fishes of the pacific coast. Spatial and temporal variation in recruitment plays an important role in population dynamics and the structuring of communities. Understanding this variation at the local and regional scale is essential for the proper management an...

A new member of the "hancocki" species complex, Acanthemblemaria castroi, is described from the Galapagos Islands. A new species, Coralliozetus springeri, is described from the Pacific coast of Panama, forming a geminate pair with C. cardonae from the Caribbean Sea. The description of the latter species is supplemented as is that of Chaenopsis schm...