Movements of lingcod (Ophiodon elongatus) tagged in Carmel Bay, California

Movements of 30 lingcod (Ophiodon elongatus) tagged with acoustic transmitters were monitored over one year using an array of acoustic receivers in Carmel Bay, California. For all tagged lingcod, residence times in the array varied from 3.8 to 100%of their respective days at liberty. On average, lingcod spent 42.5 ± 17.9 (SE) consecutive days in and 8.1 ± 1.5 (SE) consecutive days out of the array. Residency significantly decreased with total length for female lingcod, while a significant relationship was not exhibited for male lingcod. Large female lingcod, at lengths > 90% maturity, spent the least amount of time in the array but were present during the fall spawning season and briefly during the spring. There was an observed decline in residency in April for males and small female lingcod, the timing of which coincided with the post nest-guarding dispersal period for males and with the return of large females into the array. Large female lingcod were recorded at significantly greater depths within the array compared to male and small female lingcod. Lingcod exhibited strong site fidelity, with tagged fish recorded on one receiver for an average of 76.8% (± 3.7 SE) of all l-hour time bins containing signals and on two adjacent receivers for 91.0% (± 4.3 SE) of all l-hour time bins. There was no significant difference in site fidelity among sexes and size classes of tagged lingcod, and patterns of movements were not found to be different among lingcod released in high, medium, and low relief habitats

Marine reserves help preserve genetic diversity after impacts derived from climate variability: Lessons from the pink abalone in Baja California

Genetic diversity is crucial for the adaptation of exploited species like the pink abalone (Haliotis corrugata), faced with threats from climate change, overfishing and impacts associated with aquaculture production. While marine reserves are commonly used to mitigate risks to marine populations, the duration, size, location and larval connectivity needed for a reserve to help conserve genetic resources is still poorly understood. Here, we examine the effects of fishing, reserves, and restocking on the genetic diversity of 10 populations from central Baja California, Mexico, and Southern California, USA. We demonstrate that each population shows characteristic genetic signatures according to recent management decisions. We found high allelic diversity, particularly rare alleles, a larger effective population size and a lack of a recent genetic bottleneck in pink abalones within a small (0.8 km2), recently established (5 years) reserve in Baja California, compared to other fished sites after a climatic bottleneck. Higher diversity may result from the presence of older animals in the reserve. Due to its location, the reserve may also act as an important hub connecting distant populations via larval dispersal. In contrast, a population from California showed genetic isolation, loss of allelic diversity and high relatedness, consistent with the collapse of fisheries in the 1990s and their lack of recovery thereafter. In addition, a fished area in Baja California with a history of restocking for over a decade showed an increase in frequency of related individuals and high genetic differentiation from nearby sites that were consistent with the production of larvae from a few adults in the laboratory. A network of strategically placed small marine reserves that considers ocean circulation patterns could help to maintain genetic diversity and connectivity of exploited populations

Movements of Lingcod (Ophiodon elongatus) Tagged in Carmel Bay, California

Movements of 30 lingcod (Ophiodon elongatus) tagged with acoustic transmitters were monitored over one year using an array of acoustic receivers in Carmel Bay, California. For all tagged lingcod, residence times in the array varied from 3.8 to 100%of their respective days at liberty. On average, lingcod spent 42.5 ± 17.9 (SE) consecutive days in and 8.1 ± 1.5 (SE) consecutive days out of the array. Residency significantly decreased with total length for female lingcod, while a significant relationship was not exhibited for male lingcod. Large female lingcod, at lengths > 90% maturity, spent the least amount of time in the array but were present during the fall spawning season and briefly during the spring. There was an observed decline in residency in April for males and small female lingcod, the timing of which coincided with the post nest-guarding dispersal period for males and with the return of large females into the array. Large female lingcod were recorded at significantly greater depths within the array compared to male and small female lingcod. Lingcod exhibited strong site fidelity, with tagged fish recorded on one receiver for an average of 76.8% (± 3.7 SE) of all l-hour time bins containing signals and on two adjacent receivers for 91.0% (± 4.3 SE) of all l-hour time bins. There was no significant difference in site fidelity among sexes and size classes of tagged lingcod, and patterns of movements were not found to be different among lingcod released in high, medium, and low relief habitats

Movements of blue rockfish (Sebastes mystinus) off central California with comparisons to similar species.

Olive (Sebastes serranoides), black (Sebastes melanops), and blue rockfish (Sebastes mystinus) are all common inhabitants of nearshore ecosystems on the West coast of North America and important components of the recreational fishery off California. Acoustic monitoring studies indicate that olive rockfish are highly residential and that black rockfish are capable of long migrations and have less site fidelity; yet little is known about the long-term movements of blue rockfish. External tag-recapture studies indicate that blue rockfish may have intermediate movements relative to these congener nearshore species. To better understand the site fidelity, and daily and seasonal movements of blue rockfish over long (>1-year) time scales, we placed acoustic transmitters into 21 adult blue rockfish (30-41 cm total length) in Carmel Bay, California. Blue rockfish displayed intermediate movement patterns and residency relative to other similar kelp forest rockfish species. Two-thirds of tagged blue rockfish (13 fish) exhibited high residency to the study area (>12 mo). When in residence, mean home range of blue rockfish was 0.23 km2, however as many as 30% of tagged blue rockfish shifted their core home range area during the study. Most shifts in home range occurred during upwelling season, and tagged fish moved up to 3.1 km when in residence. Blue rockfish with short residence times were last detected in the study area in late winter and early spring. Blue rockfish were observed at shallower depths during day than night, likely indicative of diurnal feeding. However, over longer time scales, blue rockfish were detected at deeper depths during upwelling periods and with increased wave heights. Daily and seasonal vertical movements of blue rockfish may be influenced by upwelling conditions and local prey abundance

Lag in days, correlation, and p values associated with cross correlations among selected environmental variables and the depth anomalies of tagged blue rockfish for the periods 16 October 2006 to 15 October 2007, 1 December 2006 to 28 February 2007, and 1 April 2007 to 30 June 2007.

<p>Positive correlations indicate that tagged fish move deeper when upwelling index, atmospheric pressure, or wave height (squared) increased. Tagged fish moved deeper when temperatures declined (ns = not significant, p>0.05). Temperature was sampled at three water depths: 17, 29, and 31 m.</p

Mixed model, least-squares means estimates for depths of tagged blue rockfish in Carmel Bay in different seasons and times of day.

<p>TOD: time of day, i.e. day or night. Seasons are defined as low upwelling (December–February) and high upwelling (April–June).</p

Time series plots of environmental variables and blue rockfish depth anomalies.

<p>Plots of mean daily barometric pressure (mb), wind speed (m sec⁻¹), upwelling index (m³s⁻¹ 100 m⁻¹ of coastline), mean wave height (m²), and depth anomalies (m) of tagged blue rockfish. A daily depth anomaly was obtained by subtracting the annual mean depth of a given fish from the daily mean depth of that fish on each date of the study. Positive anomalies represent deeper mean depth than the annual mean depth; negative anomalies represent shallower mean depth than the annual mean depth.</p

<i>Sebastes mystinus</i> tagged and released in the study area in Carmel Bay, California.

<p>Tag number (ID), total length (TL), and release date of blue rockfish in the study area. Total days detected (Total d det.) is the number of days in which ≥2 signals were recorded in a 24 h period for an individual blue rockfish. Total days available (Total d avail.) is the number of days possible for each fish to be detected after receiver loss was accounted for. Residence time (Res. Time (% of d)) is the total number of days detected for each fish divided by the total number of days available in the battery life of a transmitter. Asterisks indicate individuals where residence time was adjusted for dates when receivers were temporarily lost in storms.</p