Larry G. Allen

Abundance, diversity and seasonality of fishes in Colorado Lagoon, Alamitos Bay, California

Abstract A total of 152 169 fishes from 23 species were caught in monthly beach seine hauls during 1973 in Colorado Lagoon, the small, Y-shaped, upper arm of Alamitos Bay in southern California. Four species, northern anchovy, topsmelt, slough anchovy and shiner surfperch, comprised 99% of the catch. Numbers of species and individuals were highest during the summer (May–September) and both were highly correlated with lagoon temperature which ranged from 12·8–25·0 °C. Juveniles of northern anchovy were extremely abundant in August and September. Seven species were collected in only one month and six of these only in one of the warmer months (June–August). Five species, topsmelt, shiner surfperch, California killifish, staghorn sculpin and slough anchovy, occurred in wide size ranges and during most or all of the year and were considered to be residents. Three diversity indices (Shannon-Wiener, evenness and richness) reflected the changes that occur in numbers of species and individuals during the year.

Global population structure of the tope (Galeorhinus galeus) inferred by mitochondrial control region sequence data

In order to properly manage and conserve exploited shark species, detailed analyses of their population structure is needed. Global populations of Galeorhinus galeus are in decline due to the exploitation of the fishery over the past 80 years. Currently, the genetic structure of eastern Pacific populations of G. galeus is not known and recent observations in the northeastern Pacific suggest an increase in numbers. To evaluate gene flow among populations of G. galeus, 116 samples were collected and analysed from six geographically dispersed locations: Australia, North America, South Africa, South America (Argentina and Peru), and the UK. Analysis of 968 to 1006 bp of the 1068‐bp mitochondrial control region revealed 38 unique haplotypes that were largely restricted to their collecting locality. Significant genetic structure was detected among populations (ΦST = 0.84; P < 0.000001) and migration estimates were low (Nm = 0.05–0.97). Due to an apparent lack of migration, populations of G. galeus appear to be isolated from each other with little to no gene flow occurring among them. As a consequence of this isolation, increasing numbers of G. galeus in the northeastern Pacific can be best explained by local recruitment and not by input from geographically distant populations.

A Tale of Three Tails: Cryptic Speciation in a Globally Distributed Marine Fish of the Genus Seriola

Genetic data are increasingly being applied to re-evaluate past taxonomic hypotheses and better understand the evolutionary patterns and connectivity among regional populations of cosmopolitan species. This is of particular importance for heavily exploited, commercially important species. The phylogenetic structure of the Yellowtail Jack, Seriola lalandi Valenciennes, 1833, was investigated using genetic data from 42 individuals collected from California, the Pacific coast of Baja California (Mexico), the Gulf of California (Mexico), New Zealand, Japan, South Africa, and Chile. An analysis using S. dumerili as an outgroup and combining the sequences of two mitochondrial genes (CR and COI) and four nuclear genes (RAG2, EHHADH, UBE3A, MLL) was used to determine the level of genetic divergence among samples from different geographic regions. Bayesian and Maximum Likelihood analyses utilizing combined mitochondrial gene (mtDNA) or nuclear gene (nucDNA) data supported the existence of multiple regionally restricted clades with mtDNA analysis identifying four major clades and nucDNA supporting three. Both mtDNA and nucDNA trees were very similar in topology, which was reflected in the combined total evidence phylogram. These clades were highly supported with Bayesian posterior and bootstrap probabilities ranging from 90 to 100 percent for the three major clades that were recovered in both mtDNA and nucDNA trees. These clades represent regionally specific specimens collected from the 1) Northeast Pacific, 2) Northwest Pacific, and 3) Southern Hemisphere. Morphometric analysis (MDS and ANOSIM) of available meristic data on the number of soft dorsal-fin rays, anal-fin rays, and total number of gill rakers separated specimens among the three regions identified by genetic analysis (P  =  0.05). Based on the phylogenetic structure within this taxonomic unit as evidenced by genetic data and significant meristic differences among these regional lineages, we conclude that three cryptic species currently bear the name Seriola lalandi Valenciennes, 1833. We propose the resurrection of two currently available names based on nomenclatural priority. The Northwest Pacific species name should revert to Seriola aureovittata Temminck and Schlegel (1845) (type locality Japan), and the Northeast Pacific species to Seriola dorsalis Gill (1863) (type locality Cabo San Lucas, Mexico). Seriola lalandi Valenciennes, 1833 (type locality Brazil) should apply only to the species in the Southern Hemisphere.

Reproductive Patterns of Six Populations of the Spotted Sand Bass, Paralabrax maculatofasciatus, from Southern and Baja California

Abstract The reproductive characteristics of six geographically isolated populations (n = 1150) of Spotted Sand Bass, Paralabrax maculatofasciatus, from throughout their natural range were studied from April 1992 to July 1994. Histological examination of gonads revealed the following: (1) a membrane-lined cavity or gonadal lumen was present in 9% of all males observed in this study, being present in the San Diego Bay, Los Pulpos, and Guerrero Negro populations; (2) sperm sinuses containing developing sperm were present in 65% of all females in the Anaheim Bay, Newport Bay, San Diego Bay, Los Pulpos, and Magdalena Bay populations; (3) atretic or yellow bodies were present in 76% of all males; and (5) five transitional individuals were found in the Los Pulpos and San Diego Bay populations. Both primary and secondary males were represented in all populations indicating diandric origin of males. Analysis of sex frequencies by age class and by length class for the San Diego and Los Pulpos populations showed a bimodal distribution indicative of protogynous hermaphroditism. Specimens from Anaheim Bay and Newport exhibited patterns more typical of a gonochoric reproductive pattern, whereas the Guerrero Negro and Magdalena Bay populations exhibited intermediate patterns. Only the spotted sand bass populations from San Diego Bay and Los Pulpos exhibited trends typical of protogynous hermaphroditism in both the histological and age/length population structures. Therefore, the reproductive patterns observed in the six populations of spotted sand bass are best represented by a spectrum ranging between gonochorism and protogynous hermaphroditism. The key to this diverse spectrum of strategies may be the ability of females to change sex, to delay sex change to later in life, or not to change sex at all. This reproductive plasticity also allows the females to maximize their reproductive fitness regardless of population size, breeding site densities, and accompanying mating systems.

The Fish Assemblages Inside and Outside of a Temperate Marine Reserve in Southern California

Abstract The purpose of this investigation was to evaluate the effect of a small marine reserve (established 1988) on a temperate rocky reef fish assemblage at Santa Catalina Island, California. Fish surveys on SCUBA were conducted at two reserve and two non-reserve sites from October 2002 to January 2004. Sites were similar in fish density, species richness and biomass of the entire fish assemblage. However, the adult densities of two important fishery species, California sheep-head (Semicossyphus pulcher; 7.6 ±0.5 and 5.5 ±0.4/100 m2 inside versus outside) and kelp bass (Paralabrax clathratus; 3.6 ±0.4 and 2.9 ±0.4 inside versus outside), were significantly higher within the reserve. The reserve appears to be effective in increasing density and biomass of two impacted species that were readily observed and surveyed on SCUBA.

Life History and Courtship Behavior of Black Perch, Embiotoca jacksoni (Teleostomi: Embiotocidae), from Southern California

ABSTRACT The black perch, Embiotoca jacksoni Agassiz, 1853, is a common reef fish associated with nearshore marine habitats of California, with the majority of the population occurring within the Southern California Bight. Black perch were collected throughout southern California from Santa Barbara to Carlsbad, including Santa Catalina Island, to determine their physical characteristics, growth, sex ratio, periodicity of reproduction, and length of gestation. Courtship observations were conducted using scuba along the King Harbor Breakwater in Redondo Beach, California, from January 2004 to December 2005 to verify periodicity of courting and associated reproductive behaviors. Specimens captured ranged from 75 to 220 mm standard length and from 18 to 487 g in total body weight. Seven age-classes were determined by otolith aging, with the growth rate tapering off after age-class one. Seventy percent of the individuals captured were from age-classes one to three. Growth rates did not differ between sexes. Mean monthly gonosomatic indexes for males peaked from July to November, with the highest mean occurring in October. Gestating females were found from December to May, with youngest gestating females being in age-class one. Courtship behaviors were observed within aggregations and in pairs from July to November, with males being the primary aggressors. Courtship postures occurred along the base of the reef, with pairs departing into caves for copulation. This study suggests that the black perch population within the Southern California Bight has different life history characteristics and reproductive timing than those in northern California.

Color Patterns and Associated Behaviors in the Kelp Bass, Paralabrax clathratus (Teleostei: Serranidae)

Abstract Seasonal and ephemeral color patterns in the kelp bass, Paralabrax clathratus, were studied on Santa Catalina Island, California from April 2000 to September 2002. Adults were monochromatic for part of the year (calico phase) and sexually dichromatic from April to October, with most adult males adopting bright orange snouts (OS phase). The seasonal occurrence of the OS phase in males overlapped with the spawning season, and the color was limited to ripe males. The OS phase in ripe males may function as a signal of sexual identity and sexual readiness to females. Both males and females exhibited distinct color patterns during courtship and spawning periods. During these periods, males were charcoal colored with dark black bars overlaying white spots (checkered phase), and females were often black with no visible spots (dark phase). Color patterns displayed by adults during spawning activities may facilitate mate signaling and the formation of spawning groups. Specific color patterns were also observed in relation to habitat and aggressive behaviors.

Bomb Radiocarbon Dating and Estimated Longevity of Giant Sea Bass (Stereolepis gigas)

Abstract In January 2010, a massive giant sea bass (500 lbs, 227 kg; near maximum reported size of 557 lbs, 253 kg) was captured off Santa Cruz Island by commercial gill-netters. This specimen presented a unique opportunity to estimate and validate of the potential longevity of the largest nearshore teleost of the northeastern Pacific. A transverse section of the sagittal otolith produced consistent counts of 62 opaque annuli along two different axes of the ventral sulcus region, translating into an estimated birth year of 1948. This age estimate was supported by measurements of radiocarbon (14C) in the other sagittal otolith core (within the first year of growth), relative to Δ14C reference records used for bomb radiocarbon dating. Two otolith core samples produced Δ14C values that were classified as pre-bomb (prior to ∼1958–59), indicating a minimum lifespan of 51 years. It is likely that giant sea bass can live more than 60 or 70 years based on growth zone counts, but there is no evidence in the literature or this study to support longevity of 100 years.

Demographic Parameters of Golden Spotted Rock Bass Paralabrax auroguttatus from the Northern Gulf of California

Abstract The sex ratios, growth, and mortality of the golden spotted rock bass Paralabrax auroguttatus (Serranidae) were determined for populations from Islas Encantadas and Bahia de los Angeles in the Gulf of California. Specimens ranged from 137 to 479 mm standard length and from 135 to 3,100 g. Sagittal otoliths were used to determine age. A von Bertalanffy model of growth for both populations combined was estimated as Lt = 474.4·(1 − e −0.115( t + 2.093)), where Lt is fish length at age t. This model is comparable to those for other rock basses. The relationship between length and weight (W) followed the power function W = 0.00002·L 3.0797 (r 2 = 0.96) with no difference between males and females. The mortality rate was estimated as 49% per year for fish of age 5 and older. In our Bahia de los Angeles samples, the sex ratio was significantly skewed, with more males than females. The mean size of females was significantly smaller at Bahia de los Angeles than in Islas Encantadas. Examination of the sex ...

Observations on the Mating Behavior of Captive Spotted Sand Bass (Paralabrax maculatofasciatus)

Abstract The sex allocation pattern of various populations of spotted sand bass are thought to vary from functional gonochorism to strict protogyny. The development of hypotheses explaining how such a plastic (flexible) strategy has been maintained selectively has been hindered by a general lack of information on reproductive behavior in this species. Therefore, the spawning behavior of adult, wild-caught spotted sand bass were observed in captivity under a variety of densities. Three distinct spawning modes were observed: 1) pair spawning, 2) group spawning, and 3) spawning including a sneaker male. Courtship was characterized by the following sequence: 1) a male or males approach the females, 2) one or more males make contact with the ventro-lateral surface of the female and chase the female, 3) the male contacts the ventro-lateral surface of the female and pushes her through a vertical spawning rush. Spawning behavior involved ephemeral color changes, persistent physical contact initiated by the male, short rushes beginning near structure and ending in a vertical rush with a gamete release. In general, in low density groups, reproductive activity was dominated by a single male that actively excluded smaller males from spawning. The dominant male in these groups exclusively engaged in pair spawning. Individuals in groups of higher density spawned in groups, with no observations of large males monopolizing females. These observations are consistent with the predictions of the size-advantage hypothesis regarding mating strategies in fishes. We propose that these three spawning modes and the frequency with which they occur allow the flexibility seen in the mating strategies of isolated populations of spotted sand bass.