Impact Of Fisheries Research Articles

Vulnerability assessment of species caught by the shrimp trawl fishery in northeastern Brazil

In Brazil, there are no official fisheries statistics to quantitatively assess the status of target and bycatch species. Since food security is at stake, appropriate tools are needed to maintain fisheries sustainability. One widely used “data-poor” method, despite the critics of its subjectivity, is Productivity and Susceptibility Analysis (PSA). In this study, we use PSA to assess the impact of a northeastern Brazil shrimp fishery which is socioeconomically relevant for the local population but is known to have adverse ecological impacts. The vulnerability status (high, medium, or low) of 30 species were determined by the PSA and compared with two other semi-quantitative approaches that assess stock or extinction risk. The results obtained from the PSA and other methods were partially convergent, highlighting six bycatch and one target species for which management measures or data collection should be prioritised. This study showed that PSA, when compared with other semi-quantitative methods, can constitute a valuable preliminary assessment for assessing data-poor fisheries. The integrated use of various methods is advisable in diagnosing fishery resources. However, it is essential to understand the peculiarities of each technique to appreciate its applicability and feasibility.

The Impact of Fisheries on the Economy: A Systematic Review on the Application of General Equilibrium and Input–Output Methods

In this paper, a systematic literature review on the impact of fisheries on the economy and the application of the computable general equilibrium (CGE) and input–output (IO) methods for assessing this impact is conducted. The importance of fisheries as a food source, the over exploitation of this resource, and, consequently, the impact of fisheries on the economy are the motivations behind this study. By reviewing the applications of two of the most common economic modelling tools, we aim to shine light on the state of the art and how the impact of fisheries on the economy has been addressed in the literature. In this analysis, three main themes of socio-economic, ecological, and environmental have been identified, and the application of these methods in each theme has been considered. The results show that while IO methods continue to be applied in the literature, the CGE method has experienced increased application recently, and future applications are anticipated due to its enhanced capabilities in comparison with IO models.

Mercury isotope clocks predict coastal residency and migration timing of hammerhead sharks

Abstract The management of migratory taxa relies on the knowledge of their movements. Among them, ontogenetic habitat shift, from nurseries to adult habitats, is a behavioural trait shared across marine taxa allowing resource partitioning between life stages and reducing predation risk. As this movement is consistent over time, characterizing its timing is critical to implement efficient management plans, notably in coastal areas to mitigate the impact of fisheries on juvenile stocks. In the Mexican Pacific, habitat use of the smooth hammerhead shark (Sphyrna zygaena) is poorly described, while the species is heavily harvested. Given the large uncertainties associated with the timing of out‐migration from coastal nursery grounds to offshore waters prior to reproductive maturity, a more precise assessment of smooth hammerhead shark movements is needed. Photochemical degradation of mercury imparts mass‐independent isotope fractionation (Δ199Hg) which can be used to discriminate between neonate coastal shallow habitats and the offshore deep foraging patterns of late juveniles. Here, we present the application of muscle Δ199Hg as molecular clocks to predict the timing of ontogenetic habitat shifts by smooth hammerhead sharks, based on their isotopic compositions at the initial and arrival habitats and on muscle isotopic turnover rate. We observed decreases in Δ199Hg values with shark body length, reflecting increasing reliance on offshore mesopelagic prey with age. Coastal residency estimates indicated that smooth hammerhead sharks utilize coastal resources for 2 years prior to offshore migration, suggesting a prolonged residency in these ecosystems. Policy implications. This study demonstrates how mercury stable isotopes and isotopic clocks can be implemented as a complementary tool for stock management by predicting the timing of animal migration—a key aspect in the conservation of marine taxa. In the Mexican Pacific, fishing pressure on shark species occurs in coastal habitats depleting juvenile stocks. Consequently, management decision support tools are imperative for effectively maintaining early life stage population levels over time. The finding that smooth hammerhead sharks extensively rely on highly fished habitats for 2 years after parturition supports the relevance of establishing a size limit in coastal fisheries and demonstrates how the current temporal shark fishing closure could lack efficiency for the species.

Baseline composition, quantity, and condition of bycatch in the southern Gulf of St. Lawrence spring and summer American lobster fisheries

The impact of the southern Gulf of St. Lawrence American lobster ( Homarus americanus) fishery on species bycatch is currently unknown. The composition of the incidental catch, both nonharvestable lobster (by fisheries regulations) and nonlobster species, was systematically collected over the 2015 spring and summer fishing seasons. A total of 51 948 (7147 were nonlobster taxa) individual organisms weighing 13 987.60 kg (1223.91 kg of nonlobster taxa) were captured as bycatch during 73 fishing trips. By weight per trip, the most common lobster bycatch were undersized male and females, and the highest nonlobster species catch were Atlantic rock crab ( Cancer irroratus). A semiquantitative assessment of injury and vitality was applied to bycatch as a proxy for discard mortality. The majority of the individuals assessed for visible injury were deemed uninjured (98% both fish and invertebrates); however, postrelease mortality was not measured. A smaller study in 2019 corroborated the 2015 catches and supported current assumptions that the passive gear type, the low diversity of bycatch, and the rapid hand-sorting of the trap minimize the impact of the lobster fishery on incidentally captured taxa. Further scientific monitoring is recommended to better account for all sources of mortality in stock assessments and rebuilding plans.

Estimating abundance of an elusive cetacean in a complex environment: Harbor porpoises (Phocoena phocoena) in inland waters of Southeast Alaska

The harbor porpoise (Phocoena phocoena) is common in temperate waters of the eastern North Pacific Ocean, including Southeast Alaska inland waters, a complex environment comprised of open waterways, narrow channels, and inlets. Two demographically independent populations are currently recognized in this region. Bycatch of porpoises in the salmon drift gillnet fisheries is suspected to occur regularly. In this study, we apply distance sampling to estimate abundance of harbor porpoise during ship surveys carried out in the summer of 2019. A stratified survey design was implemented to sample different harbor porpoise habitats. Survey tracklines were allocated following a randomized survey design with uniform coverage probability. Density and abundance for the northern and southern Southeast Alaska inland water populations were computed using a combination of design-based line- and strip-transect methods. A total of 2,893 km was surveyed in sea state conditions ranging from Beaufort 0 to 3 and 194 harbor porpoise groups (301 individuals) were detected. An independent sighting dataset from surveys conducted between 1991 and 2012 were used to calculate the probability of missing porpoise groups on the survey trackline (g[0]=0.53, CV=0.11). Abundance of the northern and southern populations were estimated at 1,619 (CV=0.26) and 890 (CV=0.37) porpoises, respectively. Bycatch estimates, which were only obtained for a portion of the drift gillnet fishery, suggest that mortality within the range of the southern population may be unsustainable. Harbor porpoises are highly vulnerable to mortality in gillnets, therefore monitoring abundance and bycatch is important for evaluating the potential impact of fisheries on this species in Southeast Alaska.

Vulnerability of endemic bilih fish Mystacoleucus padangensis Bleeker, 1852 in Lake Singkarak, West Sumatra, Indonesia

Bilih fish (Mystacoleucus padangensis) is an endemic species in Lake Singkarak, West Sumatra, Indonesia. It has high economic value, rich in nutrition and as an export commodity. Bilih dominated the catch in Lake Singkarak. The excessive fishing causes fish population decline. There has been an indication of stock decrease and overfishing exploitation status. Fisheries management needs to carry out to maintain the sustainability of bilih fish. This study was conducted to determine the vulnerability status of bilih fish as an information for bilih fish management. Data analysis was carried out using Productivity and Susceptibility Analysis (PSA). PSA is a semiquantitative risk assessment method used to assess the impact of fisheries on fish stocks. Based on 11 productivity and 12 susceptibility attributes, this study was conducted. The results showed that the vulnerability index was in the high category (v=2.1) and the productivity parameter value (p=1.3) lower than the susceptibility value (s=2.3), indicating bilih status is vulnerable to over fishing and need to be maintained.

How the pre and post COVID-19 era have shaped system understanding of the socioeconomic impact of small-scale inland fisheries

The current study provided a socioeconomic quantification of small-scale inland fisheries in East Africa using fish market information data for major markets in the pre (2009–2017) and post COVID-19 containment (Jan–May 2022) eras. The socioeconomic status index (SEI) incorporated 6 dimensions: access to fresh fish, access to market, available fish processing (drying) infrastructure, favourable price range, high quantity range traded, and high seasonal profit margins; using three major commercial fishes (Nile perch, Tilapia and Dagaa) and the season (pre and post COVID-19) as the main independent variables. The SEI was calculated using a segmented sociometric scale interval as: ≥ 4.21Very High ≤5.00; ≥3.41 High ≤4.20; ≥2.61 Moderate ≤3.40; ≥1.81 Low ≤2.60; and ≤1.00 Very Low ≤1.80. The socioeconomic quantification was highly dependent on COVID-19 containment periods that reflected very high (pre COVID-19 = 4.67, post COVID-19 = 4.06) impacts on small-scale inland fisheries. This suggested a negative impact of COVID-19 on small-scale inland fisheries attributed to various factors such as disrupted value chains, reduced purchasing power among the customers, struggles by businesses to compensate for losses incurred during the pandemic, and diversion of economic focus. The impact had a lower proportion on Dagaa, given its low value compared to the other two major commercial species. The quantification of fish data during a pandemic is useful to provide mitigation measures for shocks that could be anticipated in the sector for sustainable fish-food systems.

Understanding the impact of environmental variability and fisheries on the red sea urchin population in Baja California

IntroductionThe red sea urchin fishery is one of the most important fisheries in Baja California and the only urchin fishery in México; yet little is known on understanding how local, regional, and oceanic environmental variability may affect red sea urchin populations. MethodsWe analyzed how food availability, predator abundance and environmental variability could affect red sea urchin populations developing generalized linear models under different temperature conditions: Pre-heat wave, heat wave, and post–heatwave, including sites where sea surface temperature was above, below, and on average. Models included: a) biological variables: Macrocystis pyrifera (kelp) biomass, red sea urchin (Mesocentrotus franciscanus) density, sheephead (Semicossyphus pulcher), kelp bass (Paralabrax clathratus) and spiny lobster (Panulirus interruptus) catches, and b) oceanographic variables: sea surface temperature, wave power, upwelling index, multivariate El Niño index and North Pacific Gyre Oscillation index. ResultsBetween 65 and 82% of the variability observed in red sea urchin populations was explained by different combinations of variables, depending on the thermal condition analyzed. We observed that local environmental variability, such as food availability and predator harvest are highly important factors in determining red sea urchin population changes, compared to regional and oceanic scale variables such as upwelling, El Niño, or the North Pacific Gyre Oscillation. Results show that the relative importance of these variables changed depending on the spatial and temporal scale being analyzed, meaning that under “normal or average” conditions one set of variables is important, compared to extreme environmental conditions such as El Niño or “the Blob” when a different set of variables explained the observed variability. Urchin predators’ catches were correlated with urchin density during the pre-heatwave scenario, suggesting that under “average temperature” conditions the effect of fishing on predators, and consequently on urchin density is higher than local temperature, the most important variable during warm conditions. DiscussionThis study suggests that in Baja California, red sea urchin harvest has become the most important red sea urchin population control, so efforts should be encouraged and supported by state and federal agencies to promote more resilient ecosystems in the face of environmental uncertainty. Improving management of the commercial species that inhabit kelp forest, could yield benefits for the entire ecosystem, fishers, and the red sea urchin population in Mexico.

Assessing the current status of Hexanchus griseus in the Mediterranean Sea using local ecological knowledge

Fishermen from 9 countries distributed throughout the Mediterranean Sea were interviewed between May and December 2019 with the aim of compiling information about the current impact of fisheries on a large deep-water shark species, the bluntnose sixgill shark (Hexanchus griseus). A total of 382 professional fishermen belonging to 6 different gears (bottom trawling, bottom longline, drifting longline, trammel nets, gillnets and polyvalent) took part in the study. Bottom trawlers were the most interviewed fishermen (n = 148) and the best fleet coverage was obtained for bottom longline (38.89%). Results showed most captures of H. griseus occur in the Western and Central Mediterranean Sea, particularly during the warm months of the year and most commonly by bottom trawlers and bottom longliners. At-vessel mortality (AVM) was rather low in all gears but a slightly higher degree of individual mortality is suggested in trammel and gillnets. The population trend of H. griseus in the Mediterranean Sea could not be inferred from the interviews as answers were highly variable, but the overall trend in some countries may suggest this species is showing signs of population decrease. The results of this study are mostly aligned with the latest IUCN assessment but also recommend reviewing the current status of H. griseus in the Mediterranean basin. Further empirical research on post-release mortality would also be advisable to implement measures that help reduce this source of mortality.

Modelling and assessing the ecosystem of the Aegean Sea, a major hub of the eastern Mediterranean at the intersection of Europe and Asia

The aim of the present work is to present the structure of a mass balanced Ecopath model in the Aegean Sea, a highly exploited ecosystem located in the eastern Mediterranean Sea, between Greece and Turkey. The model represents the yearly average between 2003 and 2006 and includes 44 functional groups. The Aegean Sea is an overall oligotrophic system, but its northern part is the most productive area in the eastern Mediterranean Sea. Results showcased a decrease in biomass and flows with increasing trophic level, in line with the PREBAL routine and other models in the basin. Demersal species played an important role in the Aegean Sea model functioning, with squids being a true keystone group, followed by European hake. Trophic flows indicated a relatively large ecosystem, close to maturity, sharing many similarities with other Mediterranean systems. Primary production required to sustain fisheries was relatively low, while gross efficiency indicated that fisheries catches in the Aegean Sea convert less effectively the primary production. The baseline model was further expanded with the ECOIND plug-in, extracting valuable information for the ecosystem state and highlighting the importance of demersal and benthic fish and invertebrate species in the ecosystem. This model will serve as the base for the development of temporal and spatial simulations that take into account the impact of fisheries and environmental changes on the ecosystem and that can be used to explore various management scenarios.

Fish habitat use in a Caribbean mangrove lagoon system

One of the most important ecosystem services of mangroves is their role as fish habitat. While this function has been studied in many Caribbean Islands, Indo-West Pacific areas and lagoon systems in the Americas, studies in turbid estuarine lagoon systems in the Caribbean are scarce. We surveyed fish in the Ciénaga Grande de Santa Marta (CGSM), Colombian Caribbean, at five sites which had different mangrove and physicochemical characteristics. Three gillnets, parallel to the mangroves, were set at each site over six sampling cycles (n = 84); one in the mangrove, one further (∼250 m) from the mangrove and a third one furthest from the mangrove (∼400 m). We hypothesized that fish abundance and diversity, would be higher in mangrove habitats compared to mudflats, whereas biomass would be higher away from mangroves. Total fish abundance and juvenile fish abundance differed across habitats and sites, while fish biomass and fish diversity differed across sites, but not across habitats. While mangroves may be critical habitats for fish in the CGSM, mudflats may be of similar importance. Some sites had very high salinity values that together with other anthropogenic activities may limit the benefits of mangrove as critical habitats. The proportion of juveniles (67%) relative to adults of estuarine species is of concern. We recommend urgent implementation of management strategies that focus on maintaining freshwater inputs and mitigate the impact of fisheries the system is suffering.

Quantifying teleost discards in the shark fisheries of Western Australia.

Quantifying discards is essential for assessing the impact of fisheries on non-target species and the ecosystems in which these fisheries operate. In Western Australia (WA), fishers are required only to report catches of retained species. For the currently operating shark fisheries of WA, the authors quantified catch time series of discarded teleosts using data from at-sea observers collected since 1993. Sixty-two teleost species were observed in the catch of which 20 were routinely discarded. The most commonly discarded teleosts were western buffalo bream/silver drummer, Kyphosus cornelii/K. sydneyanus, and dusky morwong, Dactylophora nigricans. Annual discards peaked in the 1990s; nonetheless, current discard levels, 36.9 ± 2.1 (S.E.) t year-1 , are much lower than the overall annual retained catches (c. 1000 tyear-1 ). The catch time series reconstructed in this study are important inputs for assessing the ecosystem-based approach used for managing WA's shark fisheries.

Using off-the-shelf GPS loggers to assess co-occurrence between marine mammals and small-scale fisheries: a pilot study from the Mediterranean Sea

AbstractFisheries constitute a major threat to marine mammals globally. To evaluate the impact of small-scale fisheries (SSF) on regional under-studied marine mammal populations, we tested a novel and cost-effective approach at three data-limited locations of the central and eastern Mediterranean Sea. Using off-the-shelf GPS loggers to track SSF activities and systematic surveys to map the distribution of marine mammals, we assessed the probability of co-occurrence between SSF and marine mammals by reporting areas of spatial overlap. Spatial overlap between SSF and the core zones of marine mammal distribution (ranging between 21.85–35.4%) was observed in all three locations, indicating potential interaction hotspots. The probability of co-occurrence in those areas varied from 0.5–2.9% depending on the species. The resulting overlap between fishing activity and marine mammals may pose a threat in both directions: higher risk of species entanglement and economic burden on fishers due to gear damage. Despite the spatial and temporal limitations of this pilot study, the proposed approach can provide baseline information on SSF-marine mammal co-occurrence, particularly in financially limited regions. If applied on a larger scale, our method may be used to inform future conservation actions with the aim to reduce pressure on key populations.

Determination of the vulnerability of Korean fish stocks using productivity and susceptibility indices

Stock assessments and management of individual fish species are common tools employed for the continuous use of fish stocks; however, these tools are limited when considering the interactions between species, changes in ecosystem structure, and the influence of fisheries on overall habitats. Moreover, inaccurate stock management measures may severely impact the ecosystems. In South Korea, the marine fishery production has been decreasing since 1986. Moreover, fisheries are complex and diverse within relatively small fishing ground, and available data for ecosystem-based fisheries management (EBFM) are limited. In these situations, risk assessment is possible to identify stock status and propose effective management strategies. Productivity and susceptibility analysis (PSA), a semiquantitative risk assessment analysis, is widely used to evaluate the impact of fisheries on fish stocks. In this study, based on 8 productivity and 5 susceptibility attributes, the vulnerability score of 30 species caught by 35 fisheries were evaluated to identify and prioritize the most vulnerable fish species. Based on the results, the 30 species were classified into low (18 species), medium (10 species), and high (2 species) vulnerability groups. Therefore, management of fish species with high vulnerability should be strengthened using various management measures, including total allowable catch (TAC). In addition, quantitative stock assessment should be promoted for more effective management of these species. Moreover, PSA was found to be a useful tool for identifying and prioritizing the relatively vulnerable fish species with regard to the multispecies and multifisheries relationship in Korea.

Assessing the Stock Dynamics of Elasmobranchii off the Southern Coast of Sicily by Using Trawl Survey Data

Elasmobranchii (sharks and rays), which have peculiar and vulnerable life-history traits, are highly threatened by fishing activities. Indeed, between 53% and 71% of Mediterranean elasmobranch species are at risk of extinction. In this context, using the abundance MSY (AMSY) model, the present study provides an assessment of 20 batoids and 16 shark species in the Strait of Sicily, sampled during a bottom trawl survey from 1995 to 2020. Overall, the outputs underline a progressively improving condition for shark and ray assemblages of both shelf and eurybathic zones. As for slope-dwelling species, a horseshoe-shaped dynamic, characterized by a progressive decrease in relative harvesting pressure and an increase in relative biomass followed by an increase in fishing pressure and decrease in biomass, was detected. The dynamics of the Elasmobranchii living in the Strait of Sicily appear to be affected by changes in the fishing patterns of trawlers, showing a shift from shallow water to bathyal fishing grounds and targeting deep-water red shrimp. In this context, it seems wise to limit the impact of deep-water fisheries on Elasmobranchii by reducing fishing efforts and implementing ad hoc management measures aimed at safeguarding these vulnerable species.

Social media shines light on the "hidden" impact of nighttime guided-gigging charters on Texas' Southern Flounder fishery: A stab in the dark.

Southern Flounder (Paralichthys lethostigma) populations are declining in the Gulf of Mexico basin. This is particularly true in Texas, where this unique and culturally important fishery has been in decline since the 1980s despite increasingly stringent regulatory measures. Current angler-intercept creel surveys used to estimate recreational flounder harvest levels are conducted during daylight hours and do not account for the high levels of nighttime flounder gigging (spearing) activity, a popular and efficient harvest method for this fishery. There are legitimate scientific and logistical concerns that have prevented the use of wide-spread nighttime creel surveys to monitor the flounder gigging fishery in the past, however this has made accurate catch and effort estimates difficult to obtain. Given the concern about this economically important fishery's status, we adopted a unique approach utilizing social media to provide unprecedented information into this fishery's impact during periods that are not traditionally monitored. Specifically, we reconstructed seasonal flounder harvest and effort metrics stemming from the nighttime recreational guided flounder gigging sector over 2.6 years using guided flounder gigging charter photo archives publicly available through Facebook. These metrics show large average client party sizes, large trip harvests, and near-perfect bag limit efficiencies. Temporal trends indicated peak recreational guided flounder gigging effort and harvest occurs during the summer months, a time not traditionally associated with flounder gigging. The addition of nighttime guided-gigging recreational harvest estimates from this study to traditional daytime harvest estimates and commercial harvest estimates resulted in total annual harvest estimates nearly two times greater than current estimates. Overall, this study demonstrates the high pressure guided-gigging charters are placing on Texas' flounder fishery and illustrates the critical need for additional information on the nighttime recreational flounder fishery for both guided and private gigging anglers. Moreover, our results also demonstrate the usefulness of mining social media platforms to capture catch and effort data that are otherwise unavailable.

Monitoring the waste management system in preschool educational institutions

The article presents the results of assessing the degree of negative impact of the enterprise LLC Collective fishery "Tihiy okean" on the atmospheric air. The enterprise releases 33 pollutants into the atmosphere. Substances of the first hazard class include: dimethylamine, benzo/a/pyrene. Substances of the second hazard class include: manganese and its compounds, sulfuric acid, hydrogen sulfide, gaseous fluorides, poorly soluble fluorides, phenol, formaldehyde. All other substances belong to 3–4 hazard classes, or are not assigned to any. The work takes into account 23 sources of air pollution at the enterprise, operating at the time of the inventory of them: including 9 — organized, fourteen — unorganized. In order to analyze the compliance of indicators with hygienic standards for the quality of the surface layer of air, according to the content of 23 pollutants in it, was carried out using a unified program — UPRZA Ecolog ver. 3.0. assessment of the magnitude of surface concentrations of these impurities at the border of the sanitary protection zone of the enterprise. The results of the calculations indicate the observance of hygienic standards of atmospheric air quality, taking into account background atmospheric pollution for 23 substances emitted by the sources of the enterprise LLC "Cf" Tihiy okean. Consequently, emission limits are proposed at the level of existing emissions. The development of air protection measures is not required, but it is recommended to use the most environmentally friendly equipment currently available. The purpose of the work is to assess the degree of negative impact of the enterprise LLC Collective fishery "Tihiy okean" on the atmospheric air, determination of the level of air pollution by the enterprise.

Endangered mobulids within sustainable use protected areas of southeastern Brazil: occurrence, fisheries impact, and a new prey item

Endangered mobulids within sustainable use protected areas of southeastern Brazil: occurrence, fisheries impact, and a new prey item

Contribution of Agriculture to the Development of the Nigerian Economy

Inspite of the fact that the agricultural sector has the potential to contribute significantly to the development of the Nigerian economy, the performance of the economy over the years has not been satisfactory. This study therefore examined the contribution of the agricultural sector to economic development in Nigeria. Specifically, the study investigated the impact of crop production, livestock, fishery and forestry outputs on economic development proxied by per capita income which is measured in terms of per capita real gross domestic product in Nigeria. The analytical techniques applied include Augmented Dickey Fuller (ADF) unit root test, Autoregressive Distributed Lag (ARDL) approach, error correction model (ECM) and Granger causality test. Annual time-series data from 1981 to 2020 were used for the study. The findings indicated that crop production and forestry outputs make strong contribution to the development of the Nigerian economy while the outputs of livestock and fishery make insignificant contribution to economic development of Nigeria. The Granger causality test indicated bidirectional causality between crop production output and economic development and a unidirectional causality from livestock output to economic development. To improve the contribution of agriculture to the development of the economy, it is recommended, among other things, that the government should increase its budgetary allocation to the agricultural sector while providing subsidized agricultural inputs to farmers.

Fisheries bycatch mitigation measures as an efficient tool for the conservation of seabird populations

Abstract The impact of industrial fisheries on marine biodiversity is conspicuous in large pelagic vertebrate's fisheries bycatch. In seabirds, this led to the decline of many populations since the 1980s following the rise of global fishing effort. Bycatch mitigation measures were implemented since the 2000s, but their effects on the concerned seabird populations remain poorly quantified and understood. We studied the effects of bycatch mitigation measures on the demography of the white‐chinned petrel, one of the most bycatch impacted seabirds whose populations suffered dramatic declines before the implementation of mitigation measures. To do so we (a) built multi‐event capture–recapture models to estimate the demographic parameters of a population from Possession Island (southern Indian Ocean) over 30 years, (b) assessed the effect of climate and fishery covariates on demographic parameters, (c) built a population matrix model to estimate stochastic growth rate according to the management in fisheries bycatch and (d) estimated changes in breeding population density using distance sampling data. The population declined from the 1980s to the mid‐2000s, while trawl and longline fisheries occurred with no bycatch mitigation measures. The negative effects of fishery bycatch through additive mortality and of rat predation on breeding success were likely the main drivers of this decline. Both modelled population growth rate and observed breeding densities showed an increase since the mid‐2000s. We explained this trend by the improvement in survival probability following implementation of fishery bycatch mitigation measures and in breeding success probability with the local control of the rat population and changes in sea ice conditions on foraging grounds. Synthesis and applications. We provide a holistic approach to assess the effects of management measures by analysing datasets from sampling methods commonly employed in seabird studies. Our conclusions should encourage the eradication of invasive predatory species in seabird breeding areas and the strengthening of bycatch mitigation measures for the vulnerable seabird species, especially in international waters, but also the development of such measures considering the other marine large pelagic species threatened by fisheries bycatch (sharks, rays, turtles and marine mammals) since it could be crucial to avoid populations' extinction.