Over the past three decades, biomasses of groundfish stocks have fluctuated considerably. Average biomass ratio (B/BMSY) generally decreased in the mid- to late 1980s, with levels fluctuating around 20-30 percent of BMSY(the biomass that would maximize long-term average catches). There has been a gradually increasing trend since the mid-1990s. The percentage of stocks with low biomass (below BMSY) has exceeded 60 percent for most years in the time series, but has been declining in recent years. The percentage of stocks overfished (biomass levels below 50 percent of BMSY) exceeded 90 percent in the mid-1990s, but has since declined to levels comparable to those of the 1980 in recent years (40%). With only four years of data available following implementation of the Northeast Multispecies Sector Program, it is too early to determine if any changes have occurred in response to the program, although the percentage of stocks with low biomass has declined. Biomass indicators, like many other ecological indicators, may take many years to show patterns of change since they are subject to many different influences ( Source: www.catchshareindicators.org)
Biomass from fisheries and aquaculture
With regard to fisheries, the technical potential biomass (TPB) refers to the biomass that is available to the EU Member States in a form that can be used to benefit society. TPB represents the flows of biomass from wild capture fisheries through the supply and demand systems. Over the period 2003-2013, the TPB of the EU-28 for the North Atlantic and Mediterranean combined is estimated an overall average of 4.3 Mt (wet weight).
The top 5 EU Member States to which the largest TPB is attributed to are Denmark (791 thousand tonnes), the United Kingdom (603 thousand tonnes), Spain (442 thousand tonnes), France (428 thousand tonnes) and THE Netherlands (326 thousand tonnes).
In terms of production, the UK, French, Spanish, Portuguese and Irish fleets are the most important and collectively were responsible for 74% of the landed weight and 87% of the value landed in 2015 (JRC 2017). Based on the value of landings the French (30% of the regional landings), Spanish (26%) and UK (20%) fisheries have the highest level of landings in the Northeast Atlantic. However, Ireland and Portugal have the highest percentage of national landed value from the Northeast Atlantic at 90% and 75%, respectively. European aquaculture production represented only 1.7% of the world aquaculture production in terms of weight and 3.2% in value (Camia et al., 2018).