European Lobster Homarus Gammarus Research Articles

Non-trophic interactions amplify kelp harvest-induced biomass oscillations and biomass changes in a kelp forest ecological network model

Kelp forests are important marine ecosystems providing habitat for numerous species. Despite over 50 yr of mechanical harvesting in the Northeast Atlantic, the indirect impacts of kelp harvesting and associated habitat loss on faunal species within kelp forests remain poorly understood. We investigated the consequences of kelp harvesting by developing an allometric trophic network model for a subtidal Northeast Atlantic kelp forest (dominated by Laminaria hyperborea). Additionally, we designed a novel mechanistic model to explore the non-trophic interactions between kelp and age-class 0 Atlantic cod Gadus morhua and between kelp and European lobster Homarus gammarus, specifically focusing on the increased survival benefits provided by the kelp habitat. Simulations were conducted over a 50 yr period, incorporating harvesting cycles of 2, 5, and 9 yr, as well as low and high harvesting intensities. Our findings reveal the complex dynamics resulting from kelp harvesting. The recovery of kelp biomass was observed with 5 and 9 yr harvesting cycles, whereas a decline was observed with a 2 yr cycle. Furthermore, the non-trophic interactions facilitated a higher pre-harvest biomass for both European lobster and Atlantic cod compared to scenarios without this interaction. These results highlight the multitrophic effects of kelp harvesting and emphasize that the recovery of kelp-associated species may not necessarily align with kelp recovery, depending on harvesting intensity and recovery periods. Importantly, our study contributes to a better understanding of the ecological consequences of kelp harvesting and underscores the need for sustainable management practices to mitigate habitat loss in kelp ecosystems.

Residency and habitat use of European lobster (Homarus gammarus) within an offshore wind farm

Abstract As offshore wind energy developments increase globally in response to climate change, it is important to gain an understanding of the effects they are having on the marine environment. Whilst there is growing information on the types of organisms present within these sites, our knowledge of how species interact with these sites is limited. For the first time we examined the movements and habitat utilization of a temperate decapod, the European Lobster Homarus gammarus, using acoustic telemetry within an offshore wind farm (OWF). Innovasea V9 acoustic transmitters were externally attached to 33 individuals (carapace length = 87–113 mm) at three turbine locations within an offshore wind farm in the Irish Sea. Individuals were found to exhibit high residency to the tagging sites, with over half of tagged lobsters present at the tagging sites for 70% of the study period. Individual home ranges and core territories were calculated using 95% and 50% kernel density, respectively. Home ranges ranged from 9313.76 to 23 156.48m2 while core territories ranged from 1084.05 to 6037.38m2. Over 50% of all detections were recorded within 35 m of the scour protection. These results suggest that particular areas of habitat within fixed-turbine OWFs provide a suitable habitat for lobsters. We postulate that this is likely the result of artificial reef effects arising from the addition of artificial hard substate into previously soft sediment dominated habitats. Therefore, future fixed-turbine OWF developments across Europe may provide potential fishery opportunities as a result of artificial reef effects.

A standardized assessment of geographic variation in size at maturity of European lobster (Homarus gammarus L.) in the North East Atlantic

Abstract Assessing size at maturity for European lobster Homarus gammarus across the North East Atlantic remains a fundamental knowledge gap for this commercially valuable fishery. This study for the first time collates existing data on physiological maturity of female European lobster H. gammarus across the North East Atlantic, including new data from Scotland, Wales, and the Isle of Man. Physiological estimates of size at maturity were undertaken using 1309 lobsters from 11 locations using a standardized methodology. Carapace length (CL) at which 50% of the sampled population had reached physiological maturity (CL50) varied between populations, ranging from 82 to 92.5 mm. CL50 estimates reported here are broadly similar for historic population samples in England, but estimates for Irish samples were lower than previous results. The development of a H. gammarus specific staging guide and methodology in this study enables the future comparison of potential fluctuations in female size at maturity.

Low-impact rearing of a commercially valuable shellfish: sea-based container culture of European lobster Homarus gammarus in the United Kingdom

There is increasing interest in the aquaculture of high-value shellfish species such as European lobster Homarus gammarus. Recent years have seen the development of extractive rearing equipment requiring no additional feed input, including novel sea-based container culture (SBCC) systems designed specifically for lobster mariculture. Here, we report the results of a study which assessed the impact of SBCC systems on the local ecology surrounding a pilot-scale lobster farm (Lobster Grower) integrated into an existing mussel farm in St Austell Bay, Cornwall, UK, across 2 monitoring surveys. We assessed the impact of SBCC systems on the macrobenthic, epifaunal, and mobile species ecology across the study area through benthic grab sampling, drop-down camera, and baited-remote underwater video (BRUV) monitoring. We detected no changes to local sediment composition around SBCC systems, nor changes in macrobenthic diversity or community structure. Increased detritus and biodeposition originating from SBCC systems may be attracting increased epifaunal scavengers, while the presence of the containers and associated infrastructure may act as fish-aggregating devices and provide additional foraging opportunities for mobile fish. These extractive systems may provide low-impact and low-carbon opportunities for coastal mariculture in the face of increased global demand for shellfish.

Estimating catchability and density of the European lobster Homarus gammarus from continuous, short-term mark-recapture data

Despite the commercial and ecological importance of the European lobster Homarus gammarus, estimates of the population dynamics within socio-economically important fishing areas remain understudied. We implemented a mark-recapture approach to estimate population density, rates of loss and catchability of H. gammarus off the coast of northeast England, an important area for lobster fishers, and one of high exploitation. The short-term study used continuous trapping data from a commercial parlour trap array, fished over 6 wk. Over 9 haul occasions, 562 lobsters were marked using persistent external T-bar tags with unique ID numbers; 13.7% of these lobsters were subsequently recaptured. Catch data were used to determine the relationship between trap soak time and the effective fishing effort over time. Capture histories and effort data were analysed using a modified Cormack-Jolly-Seber (CJS) model, adapted for the short-term and continuous nature of the study. Model estimates of male lobster density varied depending on capture occasion between 732 (95% CI = 423, 1267) and 2730 (95% CI = 1585, 4701) lobsters per km2. Similarly, female density was estimated at between 2410 (95% CI = 476, 12176) and 8060 (95% CI = 1592, 40810) lobsters per km2. Low rates of loss of individuals from the area and large differences in catchability between sexes led to a female-skewed density estimate. If these findings are corroborated, the effects of sex-specific catchability and the potential for biased sex composition in populations and catches should be addressed in stock assessments and when interpreting sex ratio data in commercial catches.

Enhancing fishery-dependent information in data-poor fisheries; integrating gear-in–gear-out sensors and mobile reporting technology in a mixed Irish Sea static-gear fishery

Abstract Inshore static gear fisheries such as those targeting predominately shellfish play an import socio-economic role across the northeast Atlantic. Despite this, assessment techniques are heavily reliant on fishery dependent data which is typically aggregated over large spatial scales and lacking in key environmental and biotic data. In this study, we trialled the implementation of an enhanced electronic reporting system (EERS) and gear-in–gear-out (GIGO) technology in a data-limited, mixed species, static gear fishery for brown crab Cancer pagurus and European lobster Homarus gammarus. EERS/GIGO systems were deployed on two commercial vessels for 12 months and collected data from 812 strings, equating to 29826 pots, with precise geo-located landings per unit effort (LPUE) and environmental data. Cluster analysis identified spatially distinct patterns in fishing activity, corresponding to different target species. Generalized additive modelling was used to investigate the effect of environmental variables, inter-specific interactions and geo-location on LPUE in both species. Sea bottom temperatures had a significant positive effect on LPUE in both C. pagurus and H. gammarus. In addition, GAM analysis showed the importance of inter-specific interactions; increases in capture of competing non-target commercial species (H. gammarus/C. pagurus) resulted in the decreases in target species LPUE (C. pagurus/H. gammarus).The significant effect of environmental variables and inter-specific interactions demonstrate the value of understanding these interactions in order to produce robust standardized LPUE metrics. The EERS/GIGO system successfully demonstrated its application, and value in collecting geospatially defined fishery dependent data in historically data limited fisheries. Co-development of such an approach between fisheries administrations and industry has the potential to significantly enhance data collection and management in many data poor fisheries.

Editorial Comment on the Highlight Article “Ontogenetic changes in digestive enzyme activity and biochemical indices of larval and post larval European lobster (Homarus gammarus, L)” by Renata Goncalves et al.

Editorial Comment on the Highlight Article “Ontogenetic changes in digestive enzyme activity and biochemical indices of larval and post larval European lobster (Homarus gammarus, L)” by Renata Goncalves et al.

Impacts of Sea Bottom Temperature on CPUE of European Lobster Homarus gammarus (Linnaeus, 1758; Decapoda, Nephropidae) in the Eastern Adriatic Sea

The study describes recent decadal changes (2008–2017) in the landing biomass, fishing effort and CPUE (kg/day) data of European lobster Homarus gammarus in the eastern Adriatic Sea region, and relates these changes to increases of sea bottom temperatures detected at long-term in situ stations and modelled by an ocean numerical model (ROMS, Regional Ocean Modelling System). Modelling results were further used to quantify spatial and temporal differences of bottom temperature changes over different fishing zones. Trends of sea bottom temperature were positive and statistically significant between stations. Temporal trends of landing, effort and CPUE were also positive and significant for the northern Adriatic. Correlation analysis was used to test the relationship between winter and spring sea bottom temperatures and CPUE data of H. gammarus, separately for the northern and central Adriatic Sea, resulting in statistically significant correlations for both areas. Whether the increased CPUE in the northern Adriatic is due to increased abundance or catchability is discussed. The observed temperature changes likely reflect climate system changes recognised at the regional level and as such, lobster management measures will need to be revised and updated in the future.

Technological creep masks continued decline in a lobster (Homarus gammarus) fishery over a century

Fishery-dependent data are frequently used to inform management decisions. However, inferences about stock development based on commercial data such as Catch-Per-Unit-Effort (CPUE) can be severely biased due to a phenomenon known as technological creep, where fishing technology improves over time. Here we show how trap improvement over nine decades has driven technological creep in a European lobster (Homarus gammarus) fishery. We combined fishing data, experimental fishing with contemporary and older trap types, and information on depletion effects during fishing seasons. The resulting standardized CPUE time series indicates a 92% decline in lobster abundance between 1928 and 2019 compared to 70% if technological creep is not corrected for. Differences are most pronounced within the last 40 years when the most substantial shift in gear technology occurred: an uncorrected CPUE index suggests an 8% increase in lobster abundance during this period, while the corrected CPUE index declined by 57%. We conclude that technological creep has masked a continuous stock decline, particularly in recent decades and largely driven by the shift from one- to two-chambered traps, as well as the ability of newer trap designs to capture larger lobsters. Our study confirms the importance of adequate standardization, including technological development, when using fishery dependent CPUE for monitoring and management of data-limited fisheries.

Single nucleotide polymorphisms are suitable for assessing the success of restocking efforts of the European lobster (Homarus gammarus, L.)

The European lobster (Homarus gammarus) forms the base of an important fishery along the coasts of Europe. However, stocks have been in decline for many years, prompting new regulations in the fishery and also restocking efforts. An important feature of any restocking effort is the assessment of success in the number of released juveniles that stay and become adult over time. Here, we tested the power of a single nucleotide polymorphism (SNP) DNA marker panel developed for population assignment to correctly infer parentage on the maternal side of lobster larvae, in the absence of known fathers, using lobsters included in a current restocking effort on the Swedish west coast. We also examined the power to reconstruct the unknown paternal genotypes, and examined the number of fathers for each larval clutch. We found that the 96-SNP panel, despite only containing 78 informative markers, allowed us to assign all larvae to the correct mother. Furthermore, with ten genotyped larvae or more, confident paternal genotypes could be reconstructed. We also found that 15 out of 17 clutches were full siblings, whereas two clutches had two fathers. To our knowledge, this is the first time a SNP panel of this size has been used to assess parentage in a crustacean restocking effort. Our conclusion is that the panel works well, and that it could be an important tool for the assessment of restocking success of H. gammarus in the future.

Interactions of temperature and dietary composition on juvenile European lobster (Homarus gammarus, L.) energy metabolism and performance

Optimal rearing temperatures for European lobster Homarus gammarus in aquaculture differ from those prevalent in their aquatic ecosystems and acclimating juveniles to the prevailing temperatures before release may aid in the success of re-stocking programs. As the dietary nutritional composition is important for optimal performance of H. gammarus, in this study we aimed to investigate whether juvenile growth and energy metabolism responses to temperature variation could be modulated by the diet. Prior to the trial start, the juveniles were divided into two groups. One was maintained at 19 °C and the other gradually adapted to 13 °C. From this point and for a 24-day period, juveniles (~ 100 mg) within each temperature group were assigned one of two experimental diets: a carbohydrate-rich (HC) or a protein-rich (HP) extruded feed. Antarctic krill (AK) was used as a control diet within each temperature group. Feed intake, growth, glycogen, glucose, lactate, and protein concentrations of H. gammarus in each group were evaluated. Regardless the dietary treatment, feed intake, cephalothorax protein and glucose, and abdominal glycogen and glucose levels decreased at colder temperature. The effect of lower temperature on growth (SGR and moulting rate declines) and energy metabolism (reduction on cephalothorax glycogen and protein) was more severe in HC-fed lobsters. Results showed that the impact of lower temperature on juvenile H. gammarus can be modulated by diet highlighting the importance of designing optimized diets not only for growth and feed efficiency but also for resilience to environmental variation.

Population Genetic Structure and Connectivity of the European Lobster Homarus gammarus in the Adriatic and Mediterranean Seas.

Highly selective fishing has the potential to permanently change the characteristics within a population and could drive the decline of genetic diversity. European lobster is an intensively fished crustacean species in the Adriatic Sea which reaches high market value. Since knowledge of population structure and dynamics is important for effective fisheries management, in this study, we used 14 neutral microsatellites loci and partial mitochondrial COI region sequencing to explore population connectivity and genetic structure by comparing samples from the Adriatic Sea and the adjacent basins of the Mediterranean Sea. The obtained results suggest that neutral genetic diversity has not been significantly affected by decrease in population size due to overfishing, habitat degradation and other anthropogenic activities. Global genetic differentiation across all populations was low (FST = 0.0062). Populations from the Adriatic Sea were panmictic, while genetic differentiation was found among populations from different Mediterranean basins. Observed gene flow for European lobster suggest that populations in the north eastern Adriatic act as a source for surrounding areas, emphasizing the need to protect these populations by establishing interconnected MPAs that will be beneficial for both fisheries and conservation management.

Effects of short-term and continuous exposure to reduced salinities on the biochemical composition of larval lobster, Homarus gammarus

In coastal areas with estuarine influence, exposure to hypo-osmotic conditions may affect larval survival, development and growth. Most knowledge about effects of reduced salinity on coastal organisms is based on keeping individuals under constant conditions in the laboratory. By contrast, little is known about the effects of more realistic situations where organisms are exposed to low salinity over short time scales. Such environmental short-term fluctuations are expected to increase due to climate change. Here, we experimentally evaluated the sublethal effects of both short-term and continuous exposure to moderately reduced salinities (salinity 20 and 25; compared to seawater, salinity 32) in larvae of European lobster Homarus gammarus. Total body dry mass and biochemical composition (measured as: protein and lipid contents) were measured as response variables in Mysis stages I to III. Short-term effects of low salinity were quantified in a group of larvae kept in seawater from hatching until the time of transfer to the test salinities. After ca. 40 % of each moult cycle in seawater (determined in preliminary experiments for Mysis I, II and III), larvae were assigned to a seawater control or reduced salinities lasting for 16 h (i.e. until ca. 50 % of the time spent within the moulting cycle). Effects of continuous exposure to low salinity were quantified when larvae were exposed to the different salinities from hatching, until they reached ca. 50 % of the successive moulting stage. Surprisingly, in the Mysis II and III stages, short-term exposure to low salinity had much stronger effects on accumulation of reserves than the continuous exposure. Such effects were manifested mostly as limited accumulation, or even losses, in the lipid content as compared to reductions in the amount of protein accumulated. The most sensitive stage to exposure to low salinity was the Mysis III; by contrast in Mysis I such effects were relative weak (not always significant). Chronic exposure to low salinity also led to an increase in developmental time especially at the advanced stages. Our results highlight the importance of quantifying effects of environmental fluctuations at different time scales in order to better understand how organisms cope with realistic environmental change in the coastal zones. For H. gammarus, our results suggest that larvae respond adaptively to low salinity by maintaining protein levels at expenses of reductions in lipid accumulation and by extending the developmental time, but the capacity to elicit a fully compensatory response varies ontogenetically.

Aristotle\u2019s lobster: the image in the text

The Anatomai, a lost work written by Aristotle, must have contained a collection of various drawings and figures of species as well as their organs. In his texts (mainly the Historia animalium), Aristotle is often referring to the drawings after the description of species. Our study applies the method of the comparative view (‘Vergleichendes Sehen’) to provide an access to and reconstruction of Aristotle’s lost illustrations based on his textual descriptions. As an example, we chose the treatment of the European lobster (Homarus gammarus L., 1758) in the Aristotelian corpus as a case study. First, we analyse the etymology of the Greek term astakós referring to the lobster and provide an overview on the putative synonyms. Second, we confront the textual basis of the description with several questions concerning the degree of abstraction, the relation between text and image, and the spatial orientation of the image. Finally, we present a step-by-step reconstruction of Aristotle’s illustrations of the lobster based on the various passages dealing with its anatomy in the text of the Historia animalium. The problems which arise by a confrontation of the textual basis with hypothetical images are discussed at a more general level. We conclude that this kind of a text-based image reconstruction is only possible if the object described by Aristotle is unambiguously identifiable and still visually accessible.

Bioavailability of Microplastics to Marine Zooplankton: Effect of Shape and Infochemicals.

The underlying mechanisms that influence microplastic ingestion in marine zooplankton remain poorly understood. Here, we investigate how microplastics of a variety of shapes (bead, fiber, and fragment), in combination with the algal-derived infochemicals dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP), affect the ingestion rate of microplastics in three species of zooplankton, the copepods Calanus helgolandicus and Acartia tonsa and larvae of the European lobster Homarus gammarus. We show that shape affects microplastic bioavailability to different species of zooplankton, with each species ingesting significantly more of a certain shape: C. helgolandicus-fragments (P < 0.05); A. tonsa-fibers (P < 0.01); H. gammarus larvae-beads (P < 0.05). Thus, different feeding strategies between species may affect shape selectivity. Our results also showed significantly increased ingestion rates by C. helgolandicus on all microplastics that were infused with DMS (P < 0.01) and by H. gammarus larvae and A. tonsa on DMS-infused fibers and fragments (P < 0.05). By using a range of more environmentally relevant microplastics, our findings highlight how the feeding strategies of different zooplankton species may influence their susceptibility to microplastic ingestion. Furthermore, our novel study suggests that species reliant on chemosensory cues to locate their prey may be at an increased risk of ingesting aged microplastics in the marine environment.

Renewable energy homes for marine life: Habitat potential of a tidal energy project for benthic megafauna

An increasing number of offshore structures are being deployed worldwide to meet the growing demand for renewable energy. Besides energy production, these structures can also provide new artificial habitats to a diversity of fish and crustacean species. This study characterises how concrete mattresses that stabilise the submarine power cable of a tidal energy test site can increase habitat capacity for benthic megafauna. A five-year monitoring, which relied on both visual counts and video-based surveys by divers, revealed that these mattresses provide a suitable habitat for 5 taxa of large crustaceans and fish. In particular, two commercially valuable species, i.e. the edible crab Cancer pagurus and the European lobster Homarus gammarus, showed a constant occupancy of these artificial habitats throughout the course of the project. The shape and the number of shelters available below individual mattresses largely determine potential for colonisation by mobile megafauna. Local physical characteristics of the implantation site (e.g. substratum type, topography, exposition to current etc.) significantly impact amount and type of shelters provided by the concrete mattresses. Thus, to characterise habitat potential of artificial structures, it is not only essential to consider (i) the design of the structures, but also to (ii) account for their interactions with local environmental conditions when deployed on the seafloor.

Abundance and size of European lobsters (Homarus gammarus) and brown crabs (Cancer pagurus) inside and outside the Kåvra lobster reserve (west coast of Sweden)

Abstract The common method of using lobster-pot catch data for investigating relative abundance, sex and size distribution has serious disadvantages. This study estimates relative abundance and size of the European lobster Homarus gammarus and the brown crab Cancer pagurus using scuba diving techniques. The study areas were the Kåvra lobster reserve (Kåvra) on the Swedish west coast and three very different nearby areas where fishing for crustaceans is allowed: Gullmarsfjorden; the archipelago; and the offshore area. A total of 167 lobsters and 337 brown crabs were observed during 33 scuba dives (each 30 minutes long) in 2018-2019. The estimated mean abundance of lobsters was three to fifteen times as high at Kåvra in comparison with the other three areas (all exact showing that the statistical populations were distinct in comparison with Kåvra; Wilcoxon-Mann-Whitney Test). Dive sites in the outer part of the offshore area had the lowest abundance of lobsters although they had seemingly good lobster habitats and low fishing intensity. Large lobsters with a carapace length of ⩾15 cm were found only at Kåvra where they made up 24% of the lobsters. The proportion of large lobsters inside Kåvra continues to increase after 30 years of protection. Together, this emphasizes the impact of fishing on lobster abundance and size distribution, and indicates that limited recruitment and migration might possibly affect offshore lobster “sub populations”. Kåvra was the only area where the abundance of lobsters exceeded the abundance of brown crabs (). However, the abundance of brown crabs at Kåvra was as low as in Gullmarsfjorden () where fishing for crabs is allowed. Possible complex lobster/brown crab interactions together with other factors that might explain the low abundance of the protected brown crab at Kåvra, need to be investigated further.

A review of American lobster (Homarus americanus) records around the British Isles: 2012 to 2018

Although native to eastern Canada and the USA, American lobsters (Homarus americanus) have been reported from British coastal waters in recent years. The introduction of most have been as escapees from holding facilities or releases by members of the public for animal welfare or religious reasons. Life-history traits of H. americanus put them at a potential competitive advantage over and hybridisation with the European lobster (Homarus gammarus), the 5th most valuable seafood to the UK. While yearly reported numbers of H. americanus found in British waters have been low, a mass release of 361 H. americanus into the English Channel off Brighton, southern England, took place in June 2015. This review identified 162 records of H. americanus in British waters between 2012 and 2018, with specimens caught mainly in or around Brighton, although additional H. americanus released may have gone undetected. While this evidence suggests a growing potential for establishment of the species, further information is provided evidencing hybridisation between released H. americanus and native H. gammarus via genetic analysis. This review highlights the need for a more robust means of detecting H. americanus and other non-native species in British waters.

Inter‐ and intra‐specific interactions affecting crustacean trap fisheries—Implications for management

AbstractThe UK coastal trap fisheries target two key species, European lobster Homarus gammarus (L.) and brown crab Cancer pagurus L. Their stock status is assessed periodically using size‐based, yield‐per‐recruit analysis. Fishery trends are described using landings and, where available, effort data to estimate catch per unit of effort (CPUE), nominally proportional to abundance. Despite being caught together, assessments assume that concurrent capture of these species does not distort their individual CPUE estimates. Here, an in situ experiment tested impacts of inter‐specific and intra‐specific interactions by pre‐loading baited traps with different species and observing subsequent catches. Pre‐loaded European lobster significantly reduced brown crab catches, whereas, other species produced no such effects. The findings highlight the likely inconsistency of using CPUE as an index of abundance if landings data originate from a mixed‐species fishery in which species interactions and targeting behaviour of fishers are unknown or un‐quantified.

Spatial and temporal axes impact ecology of the gut microbiome in juvenile European lobster (Homarus gammarus)

Microbial communities within the gut can markedly impact host health and fitness. To what extent environmental influences affect the differential distribution of these microbial populations may therefore significantly impact the successful farming of the host. Using a sea-based container culture (SBCC) system for the on-growing of European lobster (Homarus gammarus), we tracked the bacterial gut microbiota over a 1-year period. We compared these communities with lobsters of the same cohort, retained in a land-based culture (LBC) system to assess the effects of the culture environment on gut bacterial assemblage and describe the phylogenetic structure of the microbiota to compare deterministic and stochastic assembly across both environments. Bacterial gut communities from SBCCs were generally more phylogenetically clustered, and therefore deterministically assembled, compared to those reared in land-based systems. Lobsters in SBCCs displayed significantly more species-rich and species-diverse gut microbiota compared to those retained in LBC. A reduction in the bacterial diversity of the gut was also associated with higher infection prevalence of the enteric viral pathogen Homarus gammarus nudivirus (HgNV). SBCCs may therefore benefit the overall health of the host by promoting the assembly of a more diverse gut bacterial community and reducing the susceptibility to disease.