Environmental Drivers of Jumbo Squid During Fishery Collapse in the Gulf of California (2019–2024)

Growth, mortality, recruitment, and yield of the jumbo squid ( Dosidicus gigas) off Guaymas, Mexico

We analyzed mantle length and age data of the whole ontogenic cycle of the jumbo squid Dosidicus gigas in the Gulf of California, Mexico, to describe its growth pattern. Several individual growth models that included asymptotic and non-asymptotic patterns were fitted to the data, and Akaike’s information criterion and multimodel inference were used to identify the model that best fit the data. The length-at-age data were divided into males and females (recruits and adults) for analysis separately and then combined to assess the overall growth pattern. The Schnute general model (ρ≠0, η≠0, where ρis the constant relative rate of the relative growth rate, ηis the incremental relative rate of the relative growth rate) was the function that best described the growth of females, males and both sexes of D. gigas together. For females, the Akaike difference and Akaike weight were 0 and 0.91, respectively; for males, the Akaike difference was also 0, but the Akaike weight was 0.39, showing that alternative growth models could explain the individual growth; these growth models were the Gompertz (L0, length at time zero), Gompertz (L∞, asymptotic length) and Schnute (ρ≠0, η = 0) models. We estimated the age and mantle length at which the growth rate changes for both sexes, estimating an age of 162.36 d (separately, 167.51 d for females and 158.98 d for males), and a length of 299.52mm for the growth inflection point (separately, 312.84 mm for females and 292.86 mm for males). Once D. gigas reaches this point, the species exhibits more gradual growth until reaching an asymptotic mantle length of 859.45 mm (for females, 904.80 mm, and for males, 828.49 mm). A comparison of the growth patterns of D. gigas reported in the Eastern Pacific indicated nonasymptotic growth of this species in the Humboldt Current and Costa Rica Dome; in contrast, asymptotic growth was identified for the western coast of Baja California and Gulf of California. The reason for this difference is unclear, and this issue will be a topic of future studies.

Got Squid? Changes in the Ecological State of the Gulf of California Since the 1940 Steinbeck-Ricketts Expedition with a Focus on Humboldt Squid W. F. Gilly (bio), Unai Markaida (bio), Carlos Robinson (bio), and Bilin Liu (bio) Introduction Although the exact number of invertebrate species collected by Steinbeck and Ricketts in conjunction with the 1940 Sea of Cortez expedition on the Western Flyer is uncertain (Brusca, this volume), it is clear that the number of cephalopod species observed was small—fewer than 1% of the species collected. In particular, Dosidicus gigas, the Humboldt or jumbo flying squid, was apparently not seen during the expedition. This stands in contrast to the remarkable ease with which this species was observed north of Santa Rosalía in the Guaymas Basin region of the Gulf of California during a 2004 retracing of the 1940 expedition during the same time of year and using the same type of vessel and similar observational methods (Sagarin et al. 2008). Dosidicus is a monocyclic, short-lived species that matures only once at a broad size range. During favorable years, large squid prevail and commonly reach a mantle length (ML) of >60 cm and a mass of 20 kg or more at maturity, with a life span of 1.5–2.0 years in the Sea of Cortez (Hoving et al. 2013). [End Page 411] Large squid of this sort supported the third- or fourth-largest commercial fishery in Mexico for the decade preceding the 2004 trip, with the vast majority of landings coming from the Guaymas Basin area (Rosa et al. 2013). These factors made it hard for even a casual observer in the Central Gulf to be unaware of Dosidicus gigas between 1995 and 2009. It thus seems that large Humboldt squid were likely not to have been abundant in the Gulf of California in the spring of 1940, and reasons for the apparent change in the status of Humboldt squid since that time have been discussed without reaching any firm conclusion (Sagarin et al. 2008). Shortly after publication of the 2008 paper, a strong El Niño in 2009–2010 influenced the Central Gulf in a profound way. Humboldt squid in this region responded to this climatic anomaly by taking on a characteristic of the tropical portion (Costa Rica to Ecuador) of their large range, where squid mature at extremely small size (~30 cm ML, ~0.1 kg) and live for only about 6 or months (Hoving et al. 2013). In addition, commercial landings crashed. Both phenomena also occurred in conjunction with the strong El Niño of 1997–1998 (Bazzino et al. 2007; Morales-Bojórquez and Nevárez-Martínez 2010). Although recovery of landings and return to a large size at maturity occurred within a few years after the 1997–1998 event (Markaida 2006), recovery has not occurred during the years after El Niño 2009–2010, a period characterized in the Central Gulf by reduced wind-driven upwelling and productivity (Robinson et al. 2016) and, as documented in the present paper, increased warming at depth (see also Frawley et al. 2019). Another strong El Niño occurred in 2015–2016. These observations suggest that the ecological state of the Gulf of California can show drastic, long-lasting alterations that involve the size of Humboldt squid. Although small Humboldt squid are probably still abundant in the Gulf (Hoving et al. 2013 and unpublished jigging data), they are clearly much less obvious (and more difficult to capture by jigging) than larger squid were a decade ago. This new awareness is relevant to the question of why Steinbeck and Ricketts did not record this species in the Sea of Cortez in 1940. We examine several possibilities in reassessing this question. First, squid may not have been of much interest to the intertidal explorers in 1940, so not much attention was paid to this group. Second, small, juvenile specimens of Dosidicus gigas were in fact collected but misidentified. Third, large Humboldt squid were temporarily absent from the Gulf during their visit because of the effects of El Niño. Fourth, [End Page 412] large (and potentially smaller) squid were absent because of chronically unfavorable...

Long-term hydrographic changes in the Gulf of California and ecological impacts: A crack in the World’s Aquarium?

Ommastrephid squid paralarvae potential nursery habitat in the tropical-subtropical convergence off Mexico

Age, growth and maturation of jumbo squid Dosidicus gigas (Cephalopoda: Ommastrephidae) from the Gulf of California, Mexico

Food and feeding of jumbo squid Dosidicus gigas in the Gulf of California and adjacent waters after the 1997–98 El Niño event

Variations in size frequency distribution, number of cohorts, and reproductive status of the jumbosquid Dosidicus gigas were analyzed in samples from seven research oceanographic cruises in the central region of the Gulf of California, Mexico from 1997 to 2008. In each station we recorded sex, gonadic phase and mantle lenght for up to 25 squids. When possible, mantle length was measured for 100 squids. We defined up to three modal groups or cohorts for several months through a multinomial distribution analysis. According to the reproductive status, squids showed a long breeding season throughout the year with two major peaks that match the birth dates estimated by the age-length chart (April to August and October to February). The size at first maturity was estimated by genders; although males were mature at a smaller size than females, no significant differences between were detected. Our results suggest that size frequency distribution andreproductive condition of jumbo squid support the hypothesis of the presence of multiple cohort in the Gulf of California, two important periods of birth, and the number of cohort’s present variation, suggesting the need for a constant monitoring of the resource for a better management of the fishery

The jumbo squid (Dosidicus gigas) has been considered a species with a semelparous life history, and this assumption has been erroneously adopted without histological evidence. Recent studies suggest that this species can spawn more than once during its life span. To identify the reproductive strategy of jumbo squid, qualitative and quantitative analyses were used in this study. Biological data were collected fortnightly from March 2008 to November 2009 off the coast of Santa Rosalía, Baja California Sur, Mexico. The histological analyses showed five stages of development: previtellogenesis, vitellogenesis, postvitellogenesis, spawning, and postspawning, with the simultaneous presence of oocytes at different substages. These results were confirmed by the presence of multiple cohorts of oocytes at each ovarian stage. Analysis applied to resting females of D. gigas confirmed that the postovulatory follicles were simultaneously found with previtellogenic oocytes denoting the ovarian recovery. The presence of postovulatory follicles at all ovarian stages and in individuals throughout the mantle length (ML) structure (from 32 to 82 cm) was an indicator of multiple spawning events. During 2008 and 2009, four ML groups (41.2, 48.5, 55.2, and 68.5 cm) and threeMLgroups (39.9, 47.8, and 53.9 cm) were observed, respectively. In conclusion, the evidence of postovulatory follicles in resting females of D. gigas indicates that the reproductive strategy of jumbo squid is iteroparity.

Sperm whales occur worldwide and feed largely on meso- and bathypelagic squid, but little is known about the behavioral ecology of this predator and its prey. In the Gulf of California, sperm whales are thought to feed on the abundant jumbo (Humboldt) squid, an ecologically and com- mercially important species. In this study, we attached satellite-linked dive recorders to 5 sperm whales and pop-up archival transmitting tags to 3 jumbo squid in the same area and time period in or- der to record their diving behavior and movements. Most (91%) deep dives by whales ranged from 100 to 500 m (average 418 ± 216.0 m) and lasted 15 to 35 min (average 27 ± 9.1 min). During daytime hours, jumbo squid spent about 75% of the time in the 200 to 400 m depth range, and sperm whales showed a similar dive-depth preference. The vertical distribution pattern of squid changed during the night, with squid spending about half the time at depths of <200 m and the remainder at 200 to 400 m. Al- though the whales shifted their nighttime diving to somewhat shallower depths, about 75% of dives remained in the 200 to 400 m depth range. Analysis of squid nighttime diving behavior, based on archival time-series data, showed that excursions into warm surface waters were often terminated by deep dives to typical daytime depths, after which the squid appeared to be relatively quiescent. Diving behavior by whales is thus consistent with the idea that they feed on jumbo squid at depth during the day, and we suggest that deep nighttime foraging may target squid that are recovering from stress af- ter recent surface activity and are therefore more susceptible to predation.

The Humboldt squid, Dosidicus gigas, is a voracious migratory predator, important prey for many species, and the target of an economically important fishery. However, information on the behavior, life history, and biomass of this species is limited. Current knowledge is based almost exclusively on fisheries records, which only contain nighttime observations and provide no information on squid distribution and behavior outside of heavily fished areas. Acoustic measurements have long been used to study fish. Development of this method for application to squid provides a noninvasive technique to assess squid numbers and sizes. This method was applied in March and April of 2007 and November of 2008 in the Gulf of California, with a focus on the Santa Rosalia region. Squid densities were as high as 25 000 per km3. Larger numbers of squid were observed at shelf breaks relative to other areas. Squid exhibited a marked diel vertical migration, with daytime depths of 300–400 m, bathymetry allowing, and nighttime depths of 0–200 m. In shallower coastal areas, the distribution of squid closely mirrored the shape of the bottom topography. This new technique is providing previously unattainable insights into the behavior and biology of this commercially and ecologically important squid species.

Ovaries of 39 large jumbo squid Dosidicus gigas (415–875 mm mantle length (ML)) of different stages of maturity from the Gulf of California and Nicaragua were analysed. Oocyte development is asynchronous during female ontogenesis, with predominance (&gt;85–90%) of small protoplasmic oocytes 0.1–0.2 mm in diameter for all stages of female maturity. Potential fecundity (PF) is determined at late immature stage II with average values around 18–21 million oocytes. The maximum PF estimated, 32 million oocytes, is so far the largest recorded for any cephalopod. PF is closely related to female size. Nicaraguan females, of smaller size (415–720 mm ML), show lower fecundity (5–15 million oocytes). Eggs were analysed in oviducts of mature females (540–875 mm ML), 7 from the Gulf of California and three females from Nicaragua. Eggs measured 0.9 × 1.1 mm in diameter and weighed 0.45 mg on average. The oviducts of the largest female (875 mm ML) held 1.2 million eggs, representing 4.6% of PF and no more than 14% of all vitelline oocyte stock of that squid. Variability in oviduct filling is very high and unrelated to ovary weight. However, a strong correlation was found between oviduct fullness and nidamental glands development. These observations suggest that spawning is extended and intermittent. A female spawns no less than half of the initial PF, and the minimal number of spawning activity events (egg batches) is roughly estimated at 8–12. During this terminal spawning stage females continue actively feeding and grow between egg-mass laying periods.

The impacts of the sea surface temperatures (SSTs) in the northern Gulf of California (GC) on warm-season rainfall in the Arizona–New Mexico (AZNM) and the northwestern Mexico (NWM) regions associated with the North American monsoon (NAM) are examined from two sets of seasonal simulations in which different SSTs were prescribed in the GC. The simulations reproduced important features in the low-level mesoscale circulations and upper air fields around the time of monsoon rainfall onset in AZNM such as sea-breeze-like diurnal variations in the low-level winds between the GC and the land, development of south-southeasterly winds over the GC and the western slope of the Sierra Madre Occidental after the onset of rainfall, and the strengthening of the 500-hPa high over AZNM around the onset of monsoon rainfall in AZNM. The simulated temporal variations in the upper air fields and daily rainfall, as well as the mesoscale circulation around the GC, suggest that the GC SSTs affect the water cycle around the GC mainly by altering mesoscale circulation and water vapor fluxes, but they have minimal impacts on the onset timing of monsoon rainfall in NWM and AZNM. With higher SSTs in the NGC, rainfall in NWM and AZNM increases in response to enhanced water vapor fluxes from the GC into the land. The enhanced onshore component of the low-level water vapor fluxes from the GC with higher GC SSTs results from two opposing effects: weakened sea-breeze-like circulation between the GC and the surrounding lands that tends to reduce the water vapor fluxes from the GC, and increased evaporation from the GC that tends to increase the water vapor fluxes. The simulations also suggest that the development of south-southeasterly low-level winds over the GC after monsoon rainfall onset plays an important role in enhancing rainfall as longer fetches over the GC can provide more water vapor into the low atmosphere.

Paralarvae of ommastrephid squid in the eastern Pacific Ocean are exceedingly difficult to identify at the species level due to extreme morphological similarities, fragmentary knowledge of early life history and ontogeny, and the co-occurrence of adults of 2 or more species in most areas. We employed molecular genetic methods to identify ommastrephid paralarvae and juveniles captured in the area of the San Pedro Martir basin in the central Gulf of California. Sequence analysis of a mitochondrial gene, cytochrome c oxidase I, identified all specimens analyzed (3 paralarvae and 11 small juveniles) as Dosidicus gigas and definitively ruled out other candidate species, specifically Sthenoteuthis oualaniensis. Paralarvae of the complete developmental size range were taken (1 to 10 mm mantle length), the smallest being the size expected for D. gigas at hatching. In addition, pairs of coupled adult D. gigas engaged in putative mating behavior were observed. Taken together, these findings indicate that mating, spawning and early development of D. gigas occur in this area.

Prolonged decline of jumbo squid (Dosidicus gigas) landings in the Gulf of California is associated with chronically low wind stress and decreased chlorophyll a after El Niño 2009–2010