Whilst the spotlight is frequently shone on advisory output, the storyboard of ICES advice on fish stocks stretches back from scientific meeting rooms all the way to the sea and the initial catching of fish for analyses.
This crucial end of the spectrum was explored and communicated during the outreach event Science in the City, a week-long science bonanza taking place in Copenhagen 21–26 June through which ICES aimed, amongst other things, to put across to the public how data are collected at sea and in what way they are used to both generate fish population size estimates for advice and understand and monitor various aspects of the marine environment.
The life cycle of a piece of data begins out at sea during one of the many research vessel surveys that ICES is involved with, either in a coordinating role or as a receiver of scientific information, in this way acting as a data hub. Over 100 of such surveys provide ICES with data each year, with the ships undertaking them clocking up an accumulative 1200 days out on the water in the process.
Here, onboard analyses of fish – both demersal and pelagic take shape in the form of targeting a sample of the fish in a given area. Many sampling activities are conducted over the Northeast Atlantic, with ICES having apportioned it into a grid of rectangular subareas from which it strategically constructs a representative picture of the entire area.
Amongst other things, surveys provide critical information on biodiversity and the status of fish and shellfish stocks. Collecting data year-by-year and long-term data series, such as that obtained from surveys in the ICES area, is key to our understanding of the oceans and how marine life and the oceans change over time.
Data though can also arrive through other channels. As well as assessments at sea, the fisherman themselves can provide the necessary information, whilst at ports from Iberia to the Norwegian Arctic coast, scientists are on hand throughout the year to monitor fish that are landed and to communicate with fishermen.
"Port sampling is an important for sustainable fisheries," explains ICES Advisory Programme Professional Officer Anne Cooper. "Scientists measure individual fish, record the number of species, vessels (and their size), and the total number of fish landed. We can monitor a stock's age structure through knowing the length of a fish and through the study of otoliths (ear bones). A healthy fish stock will have a good proportion of older fish that can spawn and contribute to future generations."
"This process requires scientists to be statisticians, biologists and diplomats—fishermen share what they're seeing in their nets and scientists can communicate what it means for the future."
Back out on the water, scientists note the hauls made by commercial fishing boats and tag fish to monitor their movements, preferred habitats, and lifespan. Logbooks, meanwhile, detail how many hours it has taken a vessel to make a catch – the so-called catch per unit of effort (or cpue) data. This is vital as increased effort may signal greater scarcity of fish.
Of course, one key reason for amassing the data is to create fish population estimates in the seas under ICES remit – a goal achieved by running them through mathematical models generate population estimates and catch forecasts at differing levels of fishing intensity.
It was a subject which proved to be a hot topic during the Science in the City festival, with one of a range of talks given by ICES scientists looking at how scientists count the number of fish in the sea. Presented by Anne Cooper, it was accompanied by a demonstration of the tagging and sampling of fish using simply plastic balls and a tub of water. The experience, a first for ICES, enabled visitors to get up close and personal with data collection and its biological importance.
"Festival goers were able to estimate the number of fish, and have fun in the process, using the mark-recapture method," Cooper reflects. "Children and parents engaged with the game, putting maths lessons into action and learning about how scientists tag fish, the significance of random sampling, the value of taking an average, and how survey data inform our knowledge of the natural world."
"Marine science often happens far from the public eye—at sea, in laboratories, and via computer models. Outreach activities such as this are important for the future of the field as they enable ICES to engage a new generation of marine scientists by bringing science out of the laboratory and into society."
ICES Science in the City booth, complete with the 'Fish Fetch' game.