Georg H. Engelhard

Centre for Environment, Fisheries and Aquaculture Science | CEFAS · Division of Environment and Ecosystems

In Namibia, fisheries are important for food security and protein provisioning, income generation and trade; but they are vulnerable to the impacts of climate change. Not only does climate change impact the marine living resources crucial to fisheries; but changes in weather, currents and storminess are affecting the safety and effectiveness of fis...

Understanding long-term change in fish populations often relies on comparing catches from historical and contemporary trawl surveys. However, such comparisons may not resolve biases associated with differences in fishing gears and their relative catchabilities. It is possible to reduce these uncertainties by replicating historical trawl gear and pr...

The mechanisms that determine the temperature tolerances of fish are poorly understood, creating barriers to disentangle how additional environmental challenges—such as CO2-induced aquatic acidification and fluctuating oxygen availability—may exacerbate vulnerability to a warming climate and extreme heat events. Here, we explored whether two acute...

Recreational fishing is popular worldwide, but many low- and middle-income coun-tries (LMICs) are experiencing increased participation and reduced catches. Like other LMICs, the recreational fishery in Namibia is facing concerns regarding its sustain-ability. Empirical evidence suggested limited knowledge of the fish and fishery as one plausible ca...

Marine communities have been impacted by human activities for centuries, yet historical data are rarely incorporated into modern conservation efforts and restoration targets. For inshore waters, survey data sets are typically lacking because they extend back by only a few decades, despite their ecological significance as nursery grounds for many fi...

Hurricanes and tropical storms have a substantial and sustained influence on fisheries globally. These threats present particularly significant challenges in Caribbean islands, where fisheries contribute towards economies, food security, and social and cultural identities. Yet, storm impacts on coastal communities and fisheries are a relatively neg...

Artisanal fisheries in Ghana account for more than two-thirds of the country’s food fish production and employ or support up to 2 million people. However, many fish stocks are close to collapse through overexploitation, especially stocks such as sardinella that are a staple food for Ghanaians. Climate change is expected to affect the fish themselve...

After drawing attention to the crucial role of marine biodiversity, including that of deep-sea ecosystems, in current scientific understanding of the ocean-climate nexus, this article highlights the limited extent to which the international climate change regime has so far addressed the ocean. The focus then shifts to how the international climate...

Sympatric flatfish predators may partition their resources in coastal environments to reduce competition and maximise foraging efficiency. However, the degree of spatial and temporal consistency in their trophic ecology is not well understood because dietary studies tend to overlook the heterogeneity of consumed prey. Increasing the spatial and tem...

Abstract Developed countries are increasingly dependent on international trade to meet seafood requirements, which has important social, environmental, and economic implications. After becoming an independent coastal state following Brexit, the UK faces increased trade barriers and changes in seafood availability and cost. We compiled a long-term...

Using analysis of field survey size-at-age data, we examine responses of European plaice (Pleuronectes platessa) to spatial differences in environmental variables in the North Sea. Using available samples of plaice aged 1–7, northern and southern migrating groups of males and females grew differently. However, length-at-age growth patterns were no...

In order to mitigate human-induced climate change, UK Government has committed to reaching ‘Net Zero’ carbon emissions by 2050, and to have reduced emissions by 78% by 2035 compared to 1990 levels (timelines for emission targets differ in detail between Devolved Administrations). Fisheries, however, typically use fossil fuels for propulsion, and fo...

The coral reefs of the Pitcairn Islands are in one of the most remote areas of the Pacific Ocean, and yet they are exposed to the impacts of anthropogenic climate change. The Pitcairn Islands Marine Protected Area was designated in 2016 and is one of the largest in the world, but the marine environment around these highly isolated islands remains p...

The global issues of climate change and marine litter are interlinked and understanding these connections are key to managing their combined risks to marine biodiversity and ultimately society. For example, fossil fuel-based plastics cause direct emissions of greenhouse gases and therefore are an important contributing factor to climate change, whi...

Aquaculture is expanding globally and is an increasingly important component of world food security. However, climate change can impact aquaculture through a variety of mechanisms varying by location and aquaculture type with implications for future productivity. Understanding the risks that climate change poses on different culture systems in diff...

Fish in coastal ecosystems can be exposed to acute variations in CO2 of between 0.2-1 kPa CO2 (2,000 - 10,000 µatm). Coping with this environmental challenge will depend on the ability to rapidly compensate the internal acid-base disturbance caused by sudden exposure to high environmental CO2 (blood and tissue acidosis); however, studies about the...

Significance We present climate risk analyses for 1) 105 ocean-dependent communities and 2) 380 fishing fleets in Europe. Our unique approach provides a perspective over the climate risks in this diverse and populous continent that is unprecedented in both its breadth and detail. We show that countries in southeast Europe as well as the United King...

Case studies in support of Caswell et al. 2020.

As climate change accelerates, species are shifting poleward and subtropical and tropical species are colonizing temperate environments. A popular approach for characterizing such responses is the community temperature index (CTI), which tracks the mean thermal affinity of a community. Studies in marine, freshwater, and terrestrial ecosystems have...

The presence of invasive species in the Mediterranean Sea is much higher than in other European seas, and understanding the reasons behind the range expansion of this invasive species is important for minimising any possible impacts to the already highly pressurised Mediterranean marine ecosystem. In this work, a brief description of sightings of t...

Summary: https://marine.copernicus.eu/news/ocean-state-report-5-summary-now-available Full report: https://www.tandfonline.com/doi/full/10.1080/1755876X.2021.1946240

Fish in coastal ecosystems can be exposed to acute variations in CO 2 that can approach 1 kPa CO 2 (10,000 μatm). Coping with this environmental challenge will depend on the ability to rapidly compensate the internal acid-base disturbance caused by sudden exposure to high environmental CO 2 (blood and tissue acidosis); however, studies about the sp...

Climate change causes warming, decreased O 2 , and increased CO 2 in marine systems and responses of organisms will depend on interactive effects between these factors. We provide the first experimental assessment of the interactive effects of warming (14 to 22°C), reduced O 2 (~3 – 21 kPa O 2 ), and increased CO 2 (~400 or ~1000 μatm ambient CO 2...

Sidney J. Holt (1926–2019) was more than a founding father of quantitative fisheries science, and the man who "helped save the great whales." His accomplishments, over a career spanning seven decades, run deeper: he was a champion of reductionism (i.e. able to identify the factors essential for management) and a systemic thinker who inspired scient...

It has proven extremely challenging for researchers to predict with confidence how human societies might develop in the future, yet managers and industries need to make projections in order to test adaptation and mitigation strategies designed to build resilience to long-term shocks. This paper introduces exploratory scenarios with a particular foc...

Seagrasses are globally important, but their extent is decreasing due to the impact of human activities and changing climatic conditions. Seagrass meadows provide vital services, but their condition and distribution are not yet well known, particularly in many small tropical Pacific islands. In 2018, observations and samples were collected from int...

Until the late 19th century, extensive beds of flat oyster Ostrea edulis populated the Central North Sea, which have vanished after intensive fisheries. At present, various initiatives are being carried out to investigate the potential to restore this former key species in the area. This historical ecological study contributes by delineating the fo...

With the majority of the global human population living in coastal regions, correctly characterising the climate risk that ocean-dependent communities and businesses are exposed to is key to prioritising the finite resources available to support adaptation. We apply a climate risk analysis across the European fisheries sector for the first time to...

The concept of ‘blue growth’, which aims to promote the growth of ocean economies whilst holistically managing marine socio-ecological systems, is emerging within national and international marine policy. The concept is often promoted as being novel, however, we show that, historical analogies exist which can provide insights for contemporary plann...

Ecologists and managers need to understand what types of communities emerge with continued human alterations to ecosystems against a background of natural change. Both natural and anthropogenic drivers are well known to affect organisms’ distributions; however, it often remains unclear where along a range of environmental and anthropogenic gradient...

Fishing – especially trawling – is one of the most ubiquitous anthropogenic pressures on marine ecosystems worldwide, yet very few long-term, spatially explicit datasets on trawling effort exist; this greatly hampers our understanding of the medium- to long-term impact of trawling. This important gap is addressed here for the North Sea, a highly pr...

Global environmental change is increasing hypoxia in aquatic ecosystems. During hypoxic events, bacterial respiration causes an increase in carbon dioxide (CO2) while oxygen (O2) declines. This is rarely accounted for when assessing hypoxia tolerances of aquatic organisms. We investigated the impact of environmentally realistic increases in CO2 on...

Describing the spatial and temporal dynamics of communities is essential for understanding the impacts of global environmental change on biodiversity and ecosystem functioning. Trait‐based approaches can provide better insight than species‐based (i.e., taxonomic) approaches into community assembly and ecosystem functioning, but comparing species an...

The Commonwealth of Dominica is a Small Island Developing State in the eastern Caribbean, that has been subject to a wide variety of natural hazards over the past century, most recently the Category 5—Hurricane Maria on 18–19 September 2017. In Dominica fishing remains important for income generation and for local food security. While there are sma...

Long-term change in marine environments is frequently investigated by comparison of historical and contemporary trawl catches. Such investigations are challenged by unquantified biases due to advances in gear technology and a lack of knowledge on the fishing power of historical trawl designs. To address this problem, historical surveys can be repea...

Sustainably managing natural resources under climate change requires understanding how species distribution shifts can impact ecosystem structure and functioning. While numerous studies have documented changes in species’ distributions and abundances in response to warming [1, 2], the consequences for the functional structure of ecosystems (i.e., c...

Fisheries and aquaculture contribute substantially to the coastal economies of the United Kingdom (UK) and Ireland, and climate change is likely to have significant impacts. Documented effects on fisheries include both losses where availability of traditional stocks are reduced, and new opportunities where abundances increase or new, incoming speci...

Phytoplankton primary production is at the base of the marine food web; changes in primary production have direct or indirect effects on higher trophic levels, from zooplankton organisms to marine mammals and seabirds. Here we present a new time-series on gross primary production in the North Sea, from 1988 to 2013, estimated using in situ measurem...

Fishers and scientists have known for over 100 years that the status of fish stocks can be greatly influenced by prevailing climatic conditions. Based on historical sea surface temperature data, the North Sea has been identified as one of 20 ‘hot spots’ of climate change globally and projections for the next 100 years suggest that the region will c...

Aim Studies focussing on long‐term changes in squid populations are rare due to limited availability of fisheries‐independent data. However, squid play an important role as predator and prey in marine food‐webs and have also become an increasingly important target for fisheries. Their short life history is thought to make them particularly sensitiv...

Fishing power, which expresses the efficiency by which vessels have the potential to catch fish, has changed dramatically over the past decades to centuries. In historical ecology, two important reasons for studying fishing power change include: (1) understanding change in the capacity (or overcapacity) of fishing fleets and their potential to expl...

How have North Sea skate and shark assemblages changed since the early 20th century when bottom trawling became widespread, while their environment became increasingly impacted by fishing, climate change, habitat degradation and other anthropogenic pressures? This paper examines long-term changes in the distribution and occurrence of the elasmobran...

As a discipline, marine historical ecology (MHE) has contributed significantly to our understanding of the past state of the marine environment when levels of human impact were often very different from those today. What is less widely known is that insights from MHE have made headway into being applied within the context of present-day and long-te...

The ICES Working Group on the History of Fish and Fisheries (WGHIST, 2015 -2017) is a forum for interdisciplinary research on social-ecological change in marine and fisheries systems over multi-decadal to multi-century timescales. It comprises a diverse group of researchers including marine biologists, fisheries scientists, historians, and historic...

This study addresses a common assumption in fisheries science: that partial fishing mortality is directly proportional to fishing effort. It is important to challenge this a priori sensible assumption, as it is also built into many models and tools used by the International Council for the Exploration of the Sea (ICES) to help provide advice and co...

Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the 1950s. Causes for the population increase last century, and understanding of whether such large numbers will be maintained in the future, are unclear. To explore this, we digitised and interrogated historical cod catch and diet datasets from the Barents...

The large fish indicator (LFI), or 'proportion of fish greater than 40 cm length in bottom trawl surveys,' is a frequently debated indicator of Good Environmental Status in European regional seas. How does the LFI respond to changes in fishing pressure? This question is addressed here through analysis of fine-scale spatial trends in the LFI within...

Well‐designed marine protected area ( MPA ) networks can deliver a range of ecological, economic and social benefits, and so a great deal of research has focused on developing spatial conservation prioritization tools to help identify important areas. However, whilst these software tools are designed to identify MPA networks that both represent bio...

A common presumption in fisheries science is that adult iteroparous fish, once matured, typically spawn in all consecutive years. Recent evidence suggests, however, that skipping of reproduction occurs more commonly than is usually believed. Adult Norwegian spring- spawning herring (Clupea harengus) undertake long annual migrations between feeding,...

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/364393/TTT_FINAL_11Jun14.pdf

Decadal changes in North Sea cod winter distribution, 1970s–2000s, based on fisheries-independent survey cpue (winter IBTS). For each decade, spatial distribution of cod cpue within the grey-shaded region is indicated by the area sizes of the black circles (proportional to cpue). In rectangles where no cpue data were available in a given decade, wh...

Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries-induce...

Globally, spatial distributions of fish stocks are shifting; but although the role of climate change in range shifts is increasingly appreciated, little remains known of the likely additional impact that high levels of fishing pressure might have on distribution. For North Sea cod we show for the first time and in great spatial detail how the stock...

Latitudinal variation in life-history traits is often explained by phenotypically plastic responses or local adap-tations to different thermal regimes. We compared growth, maturation schedules and reproductive invest-ment of female sole Solea solea between 8 populations, covering much of the species' distribution in northern Europe, with respect to...

Biological reference points are important tools for fisheries management. Reference points are not static, butmay change when a population’s environment or the population itself changes. Fisheries-induced evolution is one mechanism that can alter population characteristics, leading to “shifting” reference points by modifying the underlying biologic...