Skip to content


The State of South-West Seas in 2021

19 July 2022

Plymouth Marine Laboratory has contributed to the eighth report in the series, which brings the marine and coastal community together to record changes in local seas.
Humpback whale Above: Two baby sea stars, a type of zooplankton, photographed by scientists at Plymouth Marine Laboratory. These are two different species: late bipinnaria larvae of Luidia sarsii (on the left) and Luidia ciliaris on the right. These zooplankton are at the stage where they are about to settle out of the plankton and live in the benthos. 

Plymouth Marine Laboratory has contributed to the State of the South-West Seas 2021 report: a collaborative piece of work prepared by a group of experts working on the South-West Marine Ecosystems (SWME) partnership.

Access the full report here >>

This SWME partnership brings the marine and coastal community together annually to consider the changes that are taking place in our local seas; this is the eighth report in this series. It includes detailed chapters on oceanography, plankton, the seashore and seabed, fish and turtles, coastal birds, seals, whales, dolphins and porpoises. Management chapters include fisheries, marine protected areas, water pollution and plastics pollution. Webinars on these topics for 2021 can be viewed on this YouTube channel

The report reflects the work of both hundreds volunteer citizen scientists and professionals working in the south-west. This summary below highlights points which are covered in the chapters of the report which was published in July 2022 and the contacts you can approach for further information.

Topics include:
  • Storms  The patterns of storms in 2021 and the winter of 2022 was normal and, in many ways, unremarkable.
  • Plankton  There were no major or unusual plankton blooms in 2021. However, there was a continuation of a widespread, long-term, mainly summer decline in key elements of the food web (i.e. larger phytoplankton and copepods) during the summer months with other members of the plankton partially replacing those larger phytoplankton and copepods (i.e. of larger phytoplankton and of copepods) during the summer months, with other members of the plankton partially replacing them. Contact: Angus Atkinson (for general plankton): & Jeanette Sanders (f­or observations of gelatinous/stranded zooplankton):; South Devon Jellyfish Survey.
  • Shore and seabed marine life showed some minor changes such as a likely increase in extent of seagrass, a small (one species) increase in the number of non-native species occurring in the south-west, one 'new' warm water species recorded and increasing geographic spread of at least one other warm water species. Contact: Keith Hiscock
  • Fish   Porbeagle and thresher shark sightings maintained their recent elevated levels, but the very reduced number of sightings of the basking shark continued the pattern of recent years. The biomass of anchovies was the highest detected in recent surveys. Anchovy eggs and larvae were found in plankton samples off Plymouth, possible first indication of breeding in the area. Bluefin tuna continued to be seen routinely continuing their resurgence in south-west waters in the summer. There were interesting reports in 2021 of usually deep water species (Agentine, blue whiting and hake) in coastal waters and a growing number of records of more southern species being seen notably the silver dory and comber and rare species including Auxis sp., flying gurnard, two common two-banded sea bream and saddled sea bream as well as records of sturgeon. Contact: Douglas Herdson & Simon Thomas, sharks and rays -
  • Turtles   The number of turtle reports in the south-west was very low in 2021, and unusually more ‘hardshell’ turtles were reported than leatherback turtles. Contact: Douglas Herdson
  • Marine and coastal birds  Rat eradication is working on south-west islands notably on St Agnes and Gugh (Isles of Scilly) and Lundy, with the recovery of burrow (puffins and shearwaters) and cliff nesters continuing to increase in abundance and expand into unoccupied areas. 2021 was a reasonably good year for seabird productivity for most pursuit-diving species. Kittiwakes continued to struggle at the few remaining colonies in Devon and Cornwall. The Dorset tern colonies also had a poor season, with predation seemingly the main reason for low productivity / colony abandonment. Notable amongst trends in coastal non-breeding birds is the steep decline of black-necked grebes in the Fal Estuary since 2012. Contact: Alex Banks
  • Seals  Seals in the south-west continued to be monitored closely. This work shows that the population of grey seals in south-west England are part of a wider population in the Celtic Sea and English Channel, including the coasts of France and Ireland. The highest number of dead seals were recorded by Cornwall Wildlife Trust’s Marine Strandings Network (283 seals) including 170 white coated or moulted pups. Bycatch of seals is a major threat; one hundred and thirty-four unique entangled seals were recorded in 2021 with 18 being observed in a single survey. Disturbance was reported to be at chronic levels (at worst seals were disturbed up to once every 19 minutes). The first ever walrus was recorded in the south-west in 2021.  In March 2021 it became illegal to take, injure and kill a seal in the UK as the netsman’s defence was removed from the Conservation of Seals Act. In November 2021 it became a legal requirement for all wild capture fisheries to report incidental bycatch of marine mammals with 48 hours of returning to port. Contact: Sue Sayer -
  • Whales, Dolphins & Porpoises    The four main species of large baleen whale (humpback, fin, sei and minke) continued to be recorded in south-west waters in 2021. The developing recording effort is beginning to pay-off with a clearer pattern of likely seasonality in the sightings. Notably, for the first time four named humpback whales were recorded in south-west waters based on a photo ID database of humpbacks for the Atlantic.  The South-West coast is an important habitat for many species of dolphins and porpoises. Sightings at sea both inshore and offshore began to recover from the effects of covid with a large number of records were submitted. Common dolphins strand most often and in 2021 stranding numbers were 111 and so continued at the high end of the 20 year levels. Contact: Dan Jarvis -  Contact: Duncan Jones Abby Crosby
  • Fisheries  The south-west is especially important for fisheries at many levels.  Fisheries can adapt and develop very quickly to take advantage of new opportunities (e.g. new markets, recruitment events, or stock recovery) e.g. wrasse, sprat, cuttlefish, crawfish and bluefin tuna are all examples, but there are concerns over  declines in squid and brown crab and the ongoing issues of bass management.   Major changes to the way we manage our fisheries post-Brexit are under development and will be implemented over the next few years. Contact: Libby West -
  • Marine Protected Areas  In the SWME area, we currently have 58 Marine Protected Areas (MPAs) across the Devon, Cornwall and Isles of Scilly marine area (coastline to 12nm), 34% of the marine area is covered by an MPA designation. In terms of fisheries management measures that reduce the pressure on seabed habitats from Bottom Towed Gear (BTG), the Devon and Severn Inshore Fisheries and Conservation Authority (IFCA) has the greatest proportion of the area of MPAs (85%) protected from BTG. There has been progress in protecting areas of seabed from BTG across the SWME, with opportunities for further measures to enable nature recovery. Contact: Siân Rees  Ruth Williams  Jean-Luc Solandt -
  • Water Quality  Progress towards improving water quality in our catchments and around our coasts has stalled, and in many instances, it has gone into reverse.  Fewer water bodies achieved good or better ecological status in 2019 than they did in 2015. Many of our region’s rivers and estuaries have significant water quality issues.  Whilst the Bathing Water indicator continues to reveal reasonably encouraging results for bathing beaches, it is a poor proxy for assessing water quality as a whole and doesn’t fully capture the problem of sewage pollution. In 2021 the full scale and extent of storm overflow pollution was highlighted revealing massive and long-standing issues which have not been addressed. The Environment Agency have just released their report on 2021 ‘Water and sewerage company on pollution hits new low’ including South West Water. Contact: Steven Guilbert  
  • Plastic pollution   The work undertaken by Cornish Plastic Pollution Coalition volunteers in 2021 amounted to 69,291 hours and an economic value of £617,386. The total rubbish removed and recycled or disposed of was 310,839 kg or 310.8 tonnes! Total weight of marine littler removed was over six times that of 2018 and over three times that of 2019. Care is needed in interpreting amounts collected as there is a lot of variability in the data due to effort, many more charities recording effort and amounts, and increased knowledge of where the plastic washes up. Contact: Ruth Williams  Zara Botterell; Sarah Nelms &  Delia Webb



Share this story: