Fish Biology

Life history of fish and other aquatic organisms often involves a series of developmental stages from gametes, embryos and larvae to juveniles and adults. These life history stages deviate in their biological requirements. DTU Aqua investigates individual characteristics throughout a species’ life cycle, variation among individuals or groups, causes and effects of such variation along with interactions with other organisms and the surrounding environment. 

We use measurements at the individual level to identify and quantify biological parameters and processes that affect developmental rates, survival probability and reproductive success. These parameters and processes thereby influence population size and distribution, resilience to exploitation and environmental changes as well as ecosystem biodiversity. Insight into physiological requirements and tolerance limits are also needed to establish efficient culture conditions for new and existing species in aquaculture.   

Main themes within research into Fish Biology

Our research in fish biology focuses on interdisciplinary studies that integrate information on life history and physiological processes. It includes field and experimental studies on biological characteristics at the individual level as well as mechanisms and processes that influence organisms’ response to internal and external drivers. 

In our analyses, we use modern technology to obtain new knowledge. This includes molecular techniques, histology and stereology, high-definition digital video and image analysis as well as novel technology for physiological studies on live animals. Our research techniques, methodologies and analyses in combination provide new insight into species’ basic biology and population dynamics.   

We study an array of fishes and apply cod, herring, sprat, eel and round goby as model species to represent different life history strategies and ecological niches. Our focus is on morphological characteristics, nutritional and reproductive physiology, metabolism, respiration and bioenergetics, biochemistry and molecular mechanisms as well as behavior. 

Fish biology research comprises three main themes:

• Ecophysiology
  We identify physiological requirements, tolerances and preferences, which are important for individual development, behavior and survival. Model species: Cod and round goby.
  
  
• Growth and reproduction
  We study interactions between nutrition, growth, reproduction and environmental factors, including resource allocation, maturation patterns, hormonal mechanisms and gamete quality. Model species: Cod, eel, herring, and sprat.
  
  
• Early life history
  We focus on survival, development and behavior of early life stages related to species specific biological and physical requirements as well as their interactions with the environment. Model species: Cod and eel.

These three themes in combination link knowledge about basic requirements and physiological processes to fish welfare, growth, reproduction and development of early life history stages. Our model species applied in these studies include commercial species, key ecological species and invasive species.

Why do we do research into Fish Biology?

Gaps in biological knowledge often prevent progress in management of fish stocks and marine ecosystems, including development of conservation measures to protect marine and coastal habitats. Likewise, limitations in knowledge about species’ physiology and requirements during different life stages can hamper aquaculture advancement.

Our research in fish biology generates new insights into biological traits and eco-physiological processes that are important for an individual’s and a species’ functionality and ecology. We use our results to fill gaps in knowledge and enhance our understanding of relationships between life history traits and environmental influences that affect individual physiology and development.

We use our model species to gain knowledge about general mechanisms and processes as well as influences on life history and functional traits on vital rates and apply this insight to other species. Measurement of important traits, e.g. survival, growth and reproductive parameters and studies of processes that affect them during their lifespan, help us to identify prime mechanisms and causes of population changes and requirements for aquaculture development.

What is the research used for?

Our research generates new insight into the functioning of species and populations under changing environmental conditions and human influences on marine and coastal ecosystems. These results can be used in population and ecosystem models, e.g. for assessment and management purposes, predictions of impact of environmental changes or application in aquaculture and fisheries technology development. 

Research results on biological parameters and processes are used to build individual-based models and extensively in modelling at population and ecosystem level. Vital rates, e.g. reproductive parameters, growth and mortality, feed into stock assessment models, while basic research substantiates our understanding of mechanisms and processes, where these models do not apply, e.g. biodiversity changes and distribution capabilities of invasive species. 

A specific area of interest is research and technology development in innovation projects related to aquaculture and fisheries advancements. We focus on aquaculture technology of new or difficult species in aquaculture. This includes hormonally induced maturation and breeding technology and identification of requirements of early life stages in culture. We apply knowledge gained from nature and apply this in culture supplemented by controlled experiments and modern technology to promote progress.      

Studies frequently relate to multidisciplinary studies in international or national research projects that integrate knowledge about species, populations and drivers of ecosystems changes or enhance insights for application in aquaculture and fisheries related innovation projects. Such national or international projects provide valuable information, measures and solutions to meet the society’s challenges. This way we provide support to authorities and stakeholders.