Jose R. Marin Jarrin

The widespread loss of coastal wetlands over the past century has led to increased use of constructed wetland systems. In Humboldt Bay, California, where over 90% of tidal wetlands have been lost, several constructed wetlands with tide gates have been created to provide ecosystem services including wastewater treatment and habitat provision. However, differing management strategies may alter fish usage of these habitats, which most monitoring programs lack robust baseline data to assess. This study explored fish community composition across three constructed wetland ponds with tide gates over a 10-month period in 2024. Using a multi-gear approach including beach seines, fyke nets, and light traps, we documented 20 fish species across varying life stages, including one endangered, one threatened, and two invasive. There was significant variation in community composition and environmental conditions among and within ponds, and seasons, likely influenced by tide gate design and management. The pond with the most consistent tidal exchange during the study period supported higher species richness, greater larval recruitment, and more consistent fish movement, while ponds with restricted connectivity exhibited dominance by fewer species and lower diversity. Differences among ponds were strengthened during spring and summer, when reduced freshwater flows heavily influenced environmental conditions. These findings demonstrate the value of monitoring constructed wetlands across species and life stages and the critical role of restoring connectivity in human-made habitats. The resulting baseline dataset documents key factors potentially influencing community structure which can be utilized in the future design, creation, and continued management of constructed wetland systems.

RESEARCH NOTE Gabriel Irribarren and Jose Marin Jarrin* California State Polytechnic University, Humboldt, Department of Fisheries Biology, 1 Harpst Street, Arcata, CA 95521, USA https://orcid.org/0000-0002-4474-8323 (JMJ) * Corresponding Author: jose.marinjarrin@humboldt.edu Published 4 Nov 2024 • doi.org/10.51492/110.15 Key words: Pacific Ocean, data-poor fisheries species, Humboldt County, monitoring, Pacific razor clam, Siliqua patula Citation: Irribarren, G., and J.…

Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD] = 0.83, p = 0.0001) and richness (HSD = 0.22, p = 0.0001) in BRUVs and greater biomass (HSD = 0.32, p = 0.0002) in seine surveys compared with reference sites. Selected live‐bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD = 0.35, p = 0.0003 and HSD = 0.23, p = 0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch ( Amphistichus argenteus ), the most abundant fished species, were higher inside MPAs (K–S test D = 0.19, p < 0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.

The flagfin mojarra (Eucinostomus currani) is an important subsistence fishery resource in local Ecuadorian markets; however, very little is known about the early life history and reproductive biology of this species. In 2016 and 2017, E. currani larvae were collected at 3 sandy beaches in the Gulf of Guayaquil, Ecuador, and identified using DNA barcoding. Standard lengths ranged from 4.00–15.78 mm. We also collected otoliths to better understand the early life history of E. currani. Otoliths were used to estimate the age, population growth rate (±SE), hatch dates, and reproductive period. On average, the fish were 16.5 ± 4.5 days old, while the average growth rate was 0.70 ± 0.05 and 0.22 ± 0.16 mm per day in March and May, respectively. In the Gulf of Guayaquil, most hatch dates and the presumed reproductive activity of E. currani occurred during the wet season (December–April) when warmer water prevailed. To our knowledge, this is the first study to estimate the hatch dates and larval growth rate for a species of the family Gerreidae in the Pacific Ocean.

A variety of criteria may influence the efficacy of networks of marine protected areas (MPA) designed to enhance biodiversity conservation and provide fisheries benefits. Meta‐analyses have evaluated the influence of MPA attributes on abundance, biomass, and size structure of harvested species, reporting that MPA size, age, depth, and connectivity influence the strength of MPA responses. However, few empirical MPA evaluation studies have used consistent sampling methodology across multiple MPAs and years. Our collaborative fisheries research program systematically sampled 12 no‐take or highly protective limited‐take MPAs and paired fished reference areas across a network spanning 1100 km of coastline to evaluate the factors driving MPA efficacy across a large geographic region. We found that increased size and age consistently contributed to increased fish catch, biomass, and positive species responses inside MPAs, while accounting for factors such as latitude, primary productivity, and distance to the nearest MPA. Our study provides a model framework to collaboratively engage diverse stakeholders in fisheries research and provide high‐quality data to assess the success of conservation strategies.

The yellow-tail (Mugil galapagensis) and black-tail mullet (M. thoburni) are the Galapagos artisanal finfish fishery's most commercially important mugilids species. Despite this, knowledge about their biological characteristics is scarce and limited. In this study, the basic biological parameters of M. galapagensis and M. thoburni were estimated using empirical equations for combined sex based on total length (TL, cm) data from landings on Santa Cruz Island. The von Bertalanffy growth parameters for M. galapagensis were L∞ = 69.14 cm TL, k = 0.204 yr-1, ϕ' = 2.989, and t0 = -0.658 years, and for M. thoburni were L∞ = 62.26 cm TL, k = 0.218 yr-1, ϕ' = 2.927 and t0 = -0.631 years. The size (L50%) and age (t50%) at maturity was estimated at 35.80 cm TL (2.92 years) and 32.41 cm TL (2.74 years) for M. galapagensis and M. thoburni, respectively. The theoretical maximum age (tmax) and natural mortality (M) for M. galapagensis were 12.28 years and 0.32 yr-1, respectively. While for M. thoburni both parameters were 11.28 years and 0.35 yr-1. In conclusion, both mugilids species have slow growth, reach sexual maturity at about three years, are moderately long-lived, and have a slightly high natural mortality.

The Guayas estuary in Ecuador is the largest estuarine ecosystem on the Pacific coast of South America. This estuary provides nurseryand fisheries habitats, as well as filtering and detoxification services provided by suspension feeders, vegetation, and wetlands. Weused oceanographic and meteorological observations to understand the hydrodynamic variability of two areas in the inner part ofthe estuary, Manglares de Churute and Estero Salado, from February 2016 to February 2017. Churute has less anthropogenic impacts thanEstero Salado, which is currently uncoupled from river flow and highly influenced by Guayaquil, the second largest city in Ecuador, andadjacent shrimp pond effluents. The influences from the ocean and river on Churute include higher dissolved oxygen (DO) and lower salinity,temperature and phosphates than in Estero Salado, particularly during the wet season when the river is the dominant mode of forcing inthose warm and rainy first months of the year. Hypoxic levels (DO below 2 mg L-1) were found in Estero Salado in several stations duringthe hot, rainy season. These data suggest seasonal variability (dry/rainy season) influences the hydrographic conditions in the inner Guayasestuary mostly, adding variability to salinity, turbidity, nutrients and DO of the whole water column.

Otolith analysis allows studying multiple aspects of fish biology, including age estimation; however, otoliths collected from avian stomach content have not been used to estimate the age of ingested fish. We evaluated the potential ability to estimate the age of Pacific sardine (Sardinops sagax) from otoliths collected from blue-footed booby (Sula nebouxii) stomach contents sampled in the Galapagos Islands. Blue-footed boobies were selected because they mostly forage close to their colony (<100 m) and were, therefore, more likely to have almost intact otoliths. To estimate age, we employed three previously developed methods for otoliths. We then related these estimates to the fish's standard length and compared these relations statistically using the Akaike Information Criterion (AIC) to determine which method was most parsimonious. We collected 32 otoliths in relatively good condition, of which we aged 31 with the surface-reading method, 26 with the otolith weight method, and 29 with the posterior otolith length method. Average ages obtained with the otolith methods were 5.6 ± 1.7 yr (± standard deviation), 5.7 ± 2.0 yr, and 3.9 ± 1.5 yr, respectively. Estimates obtained with the otolith weight method had the highest correlation with standard length and the lowest AIC values of the three suggesting it was the best method for aging. Our results indicate that aging otoliths extracted from bird stomachs are possible; however, their use depends on the availability of previously developed methods and how digested the fish are when the birds return to the colony.

The authors estimated life‐history parameters of a clupeid forage fish, Opisthonema medirastre, by sampling juveniles over the course of a year in the central region of the Galápagos Islands, Ecuador. They collected 160 juveniles on the south coast of Santa Cruz Island during the wet/warm season that were 16–48 mm standard length, were 30–88 days old, had hatched at the beginning of the wet/warm season and had grown at 0.4 mm day⁻¹. The results suggest that in Galápagos, O. medirastre reproduce during the wet/warm season mostly under neutral ENSO conditions.