Oceanographic influences on the distribution and relative abundance of market squid paralarvae (Doryteuthis opalescens) off the Southern and Central California coast

Abstract

Market squid (Doryteuthis opalescens) are ecologically and economically important to the California Current Ecosystem, but populations undergo dramatic fluctuations that greatly affect food web dynamics and fishing communities. These population fluctuations are broadly attributed to 5–7‐years trends that can affect the oceanography across 1,000 km areas; however, monthly patterns over kilometer scales remain elusive. To investigate the population dynamics of market squid, we analysed the density and distribution of paralarvae in coastal waters from San Diego to Half Moon Bay, California, from 2011 to 2016. Warming local ocean conditions and a strong El Niño event drove a dramatic decline in relative paralarval abundance during the study period. Paralarval abundance was high during cool and productive La Niña conditions from 2011 to 2013, and extraordinarily low during warm and eutrophic El Niño conditions from 2015 to 2016 over the traditional spawning grounds in Southern and Central California. Market squid spawned earlier in the season and shifted northward during the transition from cool to warm ocean conditions. We used a general additive model to assess the variability in paralarval density and found that sea surface temperature (SST), zooplankton displacement volume, the log of surface chlorophyll‐a, and spatial and temporal predictor variables explained >40% of the deviance (adjusted r2 of .29). Greatest paralarval densities were associated with cool SST, moderate zooplankton concentrations and low chlorophyll‐a concentrations. In this paper we explore yearly and monthly trends in nearshore spawning for an economically important squid species and identify the major environmental influences that control their population variability.

Active acoustic telemetry tracking and tri-axial accelerometers reveal fine-scale movement strategies of a non-obligate ram ventilator

“…From our results, we hypothesize patch use may be synced with the timing of nocturnal prey movements, assuming foraging is the goal of their ARS movements. Some nocturnal invertebrates exhibit varying degrees of diurnal vertical migrations (DVMs) [81,82], and others (e.g., urchins) may take time to emerge from their protective daytime shelter habitats after sunset [83,84]. Therefore, horn sharks may time their movements to locate a patch approximately 3 h after sunset as it optimizes their chances of more easily locating dense prey patches.…”

Development of Swimming Abilities in Squid Paralarvae: Behavioral and Ecological Implications for Dispersal

“…Studies have shown that D. opalescens paralarvae migrate to the surface in the first 6 h after hatching ( Sidie and Holloway, 1999 ) and perform vertical diel migrations from 30 m (day) to the surface (night) by 14 days ( Zeidberg and Hamner, 2002 ). The highest abundances of paralarvae are found in the neuston layer at night associated with cooler SST (13–16.5°C; Koslow and Allen, 2011 ; Van Noord and Dorval, 2017 ). Our experimental results are consistent with field studies and attest that paralarvae can actively influence their fine-scale distribution by migrating vertically, becoming aggregated in areas of high food availability and adjust their dispersal patterns in the field.…”

“…Squid paralarvae are negatively buoyant ( Sidie and Holloway, 1999 ; Martins et al, 2014 ), as a result, paralarvae sink when swimming stops and must constantly jet to stay suspended and this is energetically costly. Forming schools early in life in areas of gradients of flow (vertical turbulent mixing) could assist paralarvae in holding position, minimizing the energy allocated to jetting and aggregate them with their food in upwelling areas ( Zuev, 1964 ; Koslow and Allen, 2011 ; Van Noord and Dorval, 2017 ). Indeed, D. opalescens paralarvae have been found aggregated within cyclonic gyres and eddy-induced upwelling in the Southern California Bight, where vertical mixing occurs at the frontal zone of warm and cold waters ( Zeidberg and Hamner, 2002 ).…”

“…Upon hatching, planktonic paralarvae are negatively geotactic ( Sidie and Holloway, 1999 ), passive drifters and become entrained within 3 km of shore by interacting with tidally reversing currents and cyclonic gyres. Paralarvae perform vertical diel migration ( Zeidberg and Hamner, 2002 ), and their greatest abundance is associated with cooler sea surface temperatures (SST) during La Niña events ( Van Noord and Dorval, 2017 ). Juveniles are nektonic, live on the shelf ( Zeidberg, 2014 ) and move to the slope or over deep water with development.…”

Dynamic spawning patterns in the California market squid (Doryteuthis opalescens) inferred through paralarval observation in the Southern California Bight, 2012–2019

“…Additionally, peak synchronous spawning was temporally dynamic, in that the month of peak paralarval hatching shifted from January, during 2013-2014, to December, the following hatching season. This temporal shift is likely explained by gradually warming ocean temperatures in the CCE, which causes squids, including the California market squid, to mature faster, spawn, and hatch earlier in the season (Forsythe, 2004;Van Noord & Dorval, 2017). Jackson and Domeier (2003) of California led Dosidicus gigas to adopt a small size-at-maturity phenotype, leading to the collapse of that fishery (Frawley et al, 2019).…”