ICES Journal of Marine Science

Stamp, Thomas; West, Elizabeth; Robbins, Tim; Plenty, Shaun; Sheehan, Emma

doi: 10.1093/icesjms/fsac141pmid: N/A

Estuaries provide important nursery and feeding habitat for numerous commercially and ecologically important fish, however, have been historically subject to substantial habitat alteration/degradation via environmental fluctuations, sea level rise, human activity on intertidal habitats, and adjacent land management. This review has summarized estuarine habitat use for 12 economically important finfish in the United Kingdom, of which seven were found to utilize estuarine habitats e.g. saltmarsh during their life cycle. This review reveals that ∼2500 km2 of intertidal habitat has been lost from estuaries in England and Wales since 1843. The implications of this large-scale habitat loss and continued anthropogenic disturbance within estuaries for a variety of fish species is discussed, in particular the requirement of finfish for particular habitats to be accessible and in a suitable condition. As a result of the high economic and social value of commercial and recreational fisheries, it is suggested that further research attention should investigate the spatial ecology of fish. Holistic fisheries management policies should also be considered, which would both sustainably manage fisheries landings but also account for the habitat requirements of the fisheries species.

Levin, Lisa A; Cimoli, Laura; Gjerde, Kristina; Harden-Davies, Harriet; Heimbach, Patrick; LaScala-Gruenewald, Diana; Pachiadaki, Maria; Pillar, Helen R; Smith, Leslie M; Stocks, Karen; Stopa, Justin E; Wright, Dawn J

Barnhill, Kelsey Archer

doi: 10.1093/icesjms/fsac147pmid: N/A

In this perspective, I reflect on my path to the deep sea, a field, and ecosystem that are often hard to access. Growing up in a coastal town, the seashore was my playground, but it was not until I was 18 years old that I was inspired to be a deep-sea scientist. From a Bachelor of Arts in the United States to a Master of Science in Norway and currently a PhD programme in Scotland, I have let the deep sea lead my career path with the help of supportive mentors and peers. Now, as an early career scientist with over 100 d of at-sea experience working on science, mapping, and outreach teams, I highlight the key moments that allowed me to enter the field. Looking to Horizon 2050, I share my goals for the future of deep-sea science. I hope to see a new age of ocean exploration with an increased commitment to advancing technologies, a more diverse, inclusive, and international team offshore and onshore, and a more engaged public through placing a larger focus on the deep sea in educational curricula.

Huynh, Quang C; Legault, Christopher M; Hordyk, Adrian R; Carruthers, Tom R

doi: 10.1093/icesjms/fsac066pmid: N/A

A retrospective pattern within a stock assessment occurs when historical estimates systematically increase or decrease as data are removed and has been cited as a cause of persistent overfishing. For two case studies, Gulf of Maine cod and New England pollock, we demonstrated how closed-loop simulation can be used to evaluate the impacts of retrospective patterns with respect to management objectives. Operating models (OM) representing alternative states of nature were developed and various management procedures (MP) that account for retrospective patterns in the fitted assessment models were applied. From the cod example, downward adjustment of the catch advice based on Mohn's rho was more beneficial over model averaging (MA) to meeting biomass objectives from the cod example and avoiding stock crashes. For pollock, downward adjustment and MA were robust to meeting biomass objectives at the cost of foregone catch. The ability to discriminate OMs, using indicators generated from the simulated projections, varied by MP and time for cod, but was poorer overall for pollock. This framework could be used to identify if retrospective issues generate poor management outcomes and, in some cases, alleviate pressure to identify the single most credible state of nature.

Polo, J; Punzón, A; Vasilakopoulos, P; Somavilla, R; Hidalgo, M

doi: 10.1093/icesjms/fsac125pmid: N/A

In the framework of global human-induced change, marine communities’ often respond to changing conditions abruptly reorganizing into new equilibria. These shifts are difficult to predict and often imply irreversible adjustments due to hysteresis. Unraveling the role of the forces leading regime shifts is a major challenge. We explored the temporal evolution of 63 fish species representing the Cantabrian bentho-demersal community in response to environmental changes and fishing pressure in the period 1983–2018, using survey data. Via multivariate analysis and non-additive modeling of a community index and the system's main stressors, two decadal-scale regimes were revealed, suggesting a non-linear response of the community to its environment. The Integrated Resilience Assessment framework elucidated the response mechanism to the candidate stressors and allowed quantifying resilience dynamics. The decline in fishing pressure in the 1990s was associated with a gradual transition of the system, while further decline during the 2000s eroded the resilience of the system towards changes in its stressors, leading to a discontinuous response expressed as an abrupt, possibly irreversible shift in the 2010s. Given the teleconnected character of marine ecosystems, this regional study endorses the scientific effort for actions facing the dynamic impacts of climate change on exploited marine ecosystems.

Stockin, Karen A; Amiot, Christophe; Meynier, Laureline; Purvin, Cameron; Machovsky-Capuska, Gabriel E

doi: 10.1093/icesjms/fsac133pmid: N/A

Prey detection and subsequent capture is considered a major hypothesis to explain feeding associations between common dolphins and Australasian gannets. However, a current lack of insight on nutritional strategies with respect to foraging behaviours of both species has until now, prevented any detailed understanding of this conspecific relationship. Here we combine stomach content analysis (SCA), nutritional composition of prey, a multidimensional nutritional niche framework (MNNF) and videography to provide a holistic dietary, nutritional, and behavioural assessment of the feeding association between dolphins and gannets in the Hauraki Gulf, New Zealand. Dolphins consumed ten prey species, including grey mullet (Mugil cephalus) as the most representative by wet mass (33.4%). Gannets preyed upon six species, with pilchards (Sardinops pilchardus) contributing most of the diet by wet mass (32.4%) to their diet. Both predators jointly preyed upon pilchard, jack mackerel (Trachurus spp.), arrow squid (genus Nototodarus), and anchovy (Engraulis australis). Accordingly, the MNNF revealed a moderate overlap in the prey composition niche (0.42) and realized nutritional niche (0.52) between dolphins and gannets. This suggests that both predators coexist in a similar nutritional space, while simultaneously reducing interspecific competition and maximizing the success of both encountering and exploiting patchily distributed prey. Behavioural analysis further indicated that dolphin and gannets feeding associations are likely to be mutually beneficial, with a carouselling foraging strategy and larger pod sizes of dolphins, influencing the diving altitude of gannets. Our approach provides a new, more holistic understanding of this iconic foraging relationship, which until now has been poorly understood.

Sciascia, Roberta; Guizien, Katell; Magaldi, Marcello G

doi: 10.1093/icesjms/fsac135pmid: N/A

Larval dispersal enables demographic and genetic connectivity among marine populations. For many sessile species, it is the only natural mechanism for resilience after major population disturbances, as those that have been affecting Mediterranean gorgonian species inside and outside Marine Protected Areas (MPAs). Larval dispersal simulation is a powerful tool to anticipate connectivity among populations which might be altered by modelling choices. We assessed how flow representation (resolution and vertical turbulence) and larval traits (pelagic larval duration, release timing and duration, larval vertical behaviour) influenced populations connectivity among five coastal rocky locations in the northwestern Mediterranean, four of them being designated as MPAs. We used a finer (0.3 km) and coarser (1.5 km) flow resolution in two years to assess, using a hierarchical simulation approach, the sensitivity of connectivity patterns to the above parameters. Larval traits corresponded to two gorgonian species, the neutrally buoyant Eunicella singularis and the passive sinker Paramuricea clavata. Ocean model resolution was the most influential factor on resulting connectivity patterns. When using the finer flow model resolution, connectivity patterns were equally influenced by all larval traits while vertical turbulence could be neglected. Hence, advising the design of coastal MPAs with regional connectivity estimates requires adequate flow simulation resolution.

Logan, Ryan K; Vaudo, Jeremy J; Lowe, Christopher G; Wetherbee, Bradley M; Shivji, Mahmood S

doi: 10.1093/icesjms/fsac137pmid: N/A

High recreational catch rates of istiophorid billfishes in the eastern tropical Pacific (ETP) have led to substantial eco-tourism derived economic benefits for the countries in the region, prompting many countries to mandate catch-and-release practices for recreational anglers. Previous estimates of billfish post-release behaviours and recovery periods after these physiologically stressful capture events, however, vary widely depending on the type of tag used. Using high-resolution, multi-sensor biologging tags, we provide a fine-scale, detailed view of the behaviour and recovery periods of blue marlin (Makaira nigricans; n = 9) and sailfish (Istiophorus platypterus, Istiophoridae; n = 9) caught in a typical recreational fishery in the ETP. Angling times ranged from 4 to 90 min, and fish were monitored for periods of 6–70 h after release. Blue marlin showed a characteristic long, deep dive immediately after release, with significantly greater duration associated with longer fight times, a behaviour not typical for sailfish. Diving depths were, however, much shallower than those previously reported for both species due to the shallow thermocline and oxycline present in the ETP. Data from 40 derived metrics from acceleration (i.e. tailbeat period, amplitude, pitch, etc.) and physical parameters (i.e. depth, speed, temperature, oxygen saturation, etc.) used to quantify a recovery period suggest blue marlin and sailfish recover 9.0 ± 3.2 and 4.9 ± 2.8 h after release, respectively. Our high-resolution assessment of post-release behaviour suggests that these billfish are capable of rapid physiological recovery after capture in recreational fisheries, and that catch-and-release practices like those used here can be an effective approach to conserve and sustain billfish populations in the ETP. Predicted climate change caused shallowing of the oxygen minimum zone, however, would increase the vertical habitat compression present in this region, potentially prolonging or inhibiting recovery.

Rasmuson, Leif K; Marion, Scott R; Fields, Stephanie A; Blume, Matthew T O; Lawrence, Kelly A; Rankin, Polly S

doi: 10.1093/icesjms/fsac138pmid: N/A

Combining hydroacoustics and underwater video is an effective tool for generating fish population estimates. However, hydroacoustics cannot be used to differentiate fish from the seafloor within an area known as the acoustic dead zone. A common way to address this is to exclude data near the bottom. The effect of this exclusion zone on population estimates of nearshore semi-pelagic rockfish is unknown. This study explores the effect of a near bottom (0–1 m) exclusion zone by comparing ROV video data to data from a combined hydroacoustic and video method. Higher densities of semi-pelagic species (Black and Blue/Deacon Rockfish) were observed in the combined acoustic and video method, suggesting that most of the population resides above the exclusion zone. Demersal rockfish observed by the ROV did not contaminate acoustic data of semi-pelagic species, since they remained within the exclusion zone. Results demonstrate that extrapolation of school data into the exclusion zone provided a realistic correction to the acoustic data for Black Rockfish. Our work demonstrates that excluding the data within 1 m of the bottom does not negatively affect the ability of the combined video hydroacoustic method to sample semi-pelagic rockfish.

Pascoe, Penelope; Raymond, Ben; Carmichael, Noel; McInnes, Julie

doi: 10.1093/icesjms/fsac139pmid: N/A

Macquarie Island's king penguin (Aptenodytes patagonicus) population has changed dramatically over recent centuries. Following near decimation from commercial exploitation during the 19th and early 20th centuries, chick numbers increased rapidly from 1930–1980. Since then, the population's trajectory has remained unreported, and environmental factors potentially influencing the population are poorly understood. From 2007–2020, king penguin chicks were censused annually. Chick numbers fluctuated between years, ranging from 33,513–78,714. Overall, the numbers decreased at 1.06 ± 0.03% per annum. While further studies are required to infer causality, annual chick numbers were negatively correlated with environmental conditions on land and at sea. Heavy rainfall, total rainfall, and maximum east coast wave height during incubation correlated with fewer chicks that year. Warmer sea surface temperatures in the foraging region of adult king penguins during incubation and early chick-rearing also correlated with lower chick numbers. While interannual variability and the long generation time of king penguins makes it unclear if the decrease in chick numbers represent a decrease in the breeding population, it is clear the late 20th century rapid increase in Macquarie Island's breeding population has ceased. Ongoing monitoring will establish if this is indicative of the population stabilising or an ongoing population decline.