Supporting our Seas

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Stephens Rickard supported 4 crab and lobster survey sites along the Sussex coastline in 2024

Stephens Rickard chose to take action towards protecting marine life in 2024, by sponsoring 4 crab and lobster survey sites as part of the Sussex Kelp Recovery Project. Stephens Rickard worked with GreenTheUK to fund innovative research led by Blue Marine Foundation and University of Sussex. This report outlines the findings from the 2023 survey report and includes data from Stephens Rickard survey sites.

Introduction

In the late 1970s, abundant kelp beds between Selsey and Shoreham-by-Sea teemed with life. This biodiverse environment played a key ecological role providing shelter, feeding and nursery grounds for marine life, including commercially important crustaceans. However, by the end of the 1990s, 96 per cent of the kelp had disappeared. Among the factors that caused the kelp to disappear were the great storm of 1987 and intensive fishing activity in the area using heavy trawl nets (trawling), which, when dragged along the seafloor, can destroy seabed habitats.

In 2010, an inshore habitat map commissioned by Sussex Inshore Fisheries and Conservation Authority (IFCA) showed how habitats in the area had changed and ignited discussions about kelp's role in the ecosystem. Over subsequent years, Sussex IFCA, who manage the area from the shoreline out to 6 nautical miles, created a compelling case for a new piece of legislation which aimed to protect essential fish and marine habitats and support sustainable inshore fisheries: the Sussex Nearshore Trawling Byelaw.

The Nearshore Trawling Byelaw (NTB) came into effect in March 2021, prohibiting trawling over 304 square kilometres of seabed. To understand the ecological, social and economic value of kelp and the benefits of the Byelaw on kelp recovery, local inshore fisheries and the wider ecosystem, Blue Marine and partners of the Sussex Kelp Recovery Project have established an extensive monitoring and research programme.

Part of this research includes a long-term programme of potting surveys to understand the impact of the Byelaw on commercial crustacean fisheries, specifically European lobster (Homarus gammarus) and brown crab (Cancer pagurus) (also known as edible crab). The first surveys were carried out in 2021, within six months of the introduction of the Byelaw, establishing a baseline against which future changes can be measured.

Methodology

In 2021, data was collected on crab and lobster abundance, carapace size, weight, sex ratio and condition at 12 sites around Selsey, both within and outside the Nearshore Trawling Byelaw area (stated as “trawling exclusion zone” or “NTB” throughout the report), with the help of local fishermen. In 2022, surveys were conducted at a total of 24 sites, extending the range of the project to include sites off Brighton and Eastbourne as well as Selsey, again surveying on board local fishing boats. In August 2023, the aim was to further increase the number of sites surveyed across the Byelaw area to increase replication. However, due to weather and the availability of fishermen, only 21 sites were able to be surveyed around Selsey Bill and Brighton (Figure 1). This allowed the collation of a three-year dataset at Selsey, where the effects of the Byelaw on crab and lobster populations could be monitored over time. Therefore, the analysis undertaken in 2023 included Selsey data only and the other data collected will form part of the wider long-term dataset in future years.

To understand the effect of the Nearshore Trawling Byelaw on commercial crustacean species over time, the independent variables in this analysis were ‘Treatment’, split into two categories of ‘NTB’ and ‘Outside’ the trawling exclusion zone, and ‘Year’ (2021, 2022 and 2023) to analyse differences between years. Treatments were defined as:

  • NTB: inside the trawling exclusion zone (Nearshore Trawling Byelaw area)
  • Outside: outside the trawling exclusion zone (Open Control sites)

In order to see if there were any differences in crab and lobster population metrics inside and outside the trawling exclusion zone in 2023 across a wider area, the 2023 data from Selsey and Brighton was combined and a second supplementary test for significant differences was completed.

image Figure 1: Survey sites used in data analysis across Selsey and Brighton from 2021, 2022 and 2023

Key findings

  • Overall, the results from the three-year dataset at Selsey showed that there were no significant differences in crab or lobster population metrics between inside and outside the trawling exclusion zone or between years of 2021, 2022 and 2023. This is expected, given that this survey was undertaken only two years and five months from when the Nearshore Trawling Byelaw was designated.
  • The results from Selsey show a gradual increase in lobster abundance over the three years in both treatments between 2021 and 2023 (Figure 2), aligning with anecdotal reports from fishermen.
  • A gradual decline of brown crab is also shown at Selsey in both treatments between 2021 and 2023 (Figure 3), a similar trend to other regions across the UK.
  • In 2023, brown crab condition reduced across both treatments from 2021 and 2022 data at Selsey (Figure 4). There was also an occurrence of a moribund brown crab. The cause of decline and brown crab death is not known, but it is suggested that rapidly changing water temperatures could be having an effect, due to the time of year the deaths are occurring.
  • Despite not being significant, another notable trend seen at Selsey is the higher number of small lobsters (below Minimum Conservation Reference Size) inside the trawling exclusion zone across all years (Figure 5). This could potentially suggest that the exclusion zone is providing shelter and nursery grounds for juvenile individuals.

Conclusion

The pot fishery survey completed in August 2023 was conducted two years and five months after designation of the Byelaw. As this data is part of a long-term study, it is still too early to make solid conclusions on the impact of the Nearshore Trawling Byelaw on brown crab and European lobster fisheries. However, it is expected, as evidenced in other areas where trawling is removed, that as the kelp beds and other habitats recover, crab and lobster populations will increase in number, there will be a greater number of larger mature individuals and juvenile individuals, and individuals caught would be in better condition.

During the surveys in 2022 and 2023, observations of sedimentation in crab and lobster potting areas were reported by all fishermen, especially out of Brighton Marina. Such reports are important to note due to the potential influence of sediment on kelp settlement and growth and crustaceans, which could alter their response to spatial management measures.

Appendices

image Figure 2: Mean abundance (Catch Per Unit Effort (CPUE)) of lobster caught inside the Nearshore Trawline Byelaw area (NTB) and Outside zone across 2021, 2022 and 2023 at Selsey.
image Figure 3: Mean abundance of brown crab caught inside the Nearshore Trawling Byelaw area (NTB) and Outside and between 2021, 2022 and 2023 at Selsey.
image Figure 4: Percentage frequency of brown crab caught in each Condition category across 2021, 2022 and 2023 at Selsey and between a) inside the Nearshore Trawling Byelaw area (NTB) and b) Outside.
image Figure 5: Mean abundance of lobster caught below MCRS inside the Nearshore Trawling Byelaw area (NTB) and outside the trawling exclusion zone between 2021, 2022 and 2023 at Selsey.

Acknowledgements

GreenTheUK would like to extend a huge thank you to Blue Marine Foundation and their skippers, crew, and individuals who assisted with these surveys.

Research assistants: Madi Bowden-Parry (University of Exeter), Seshi Humphrey-Ackumey (Blue Marine Foundation), Vanessa Simons (Sussex IFCA), and Ella Garrud (Sussex Wildlife Trust).

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Species this project aims to support

Edible Crab : Cancridae

Edible Crab

If you’ve ever been rock-pooling on one of the UK’s glorious beaches, the chances are you’ve encountered the shore crab. This common crustacean can grow up to 9cm wide and is usually either green, orange or red. The edible brown crab, meanwhile, is around twice that size and thousands of tonnes of edible crabs are caught annually in the English Channel.

Common Lobster : Homarus Gammarus

Common Lobster

You might think of lobsters as being red, but in fact that only happens when it is cooked; in the wild, lobsters are blue! They have two pincers of different sizes: one to crush food and one to tear it. Lobsters have very bad eyesight, but an excellent sense of smell and taste.

Whelk : Buccinum Undatum

Whelk

The common whelk is found all around the UK’s coast and is the largest sea snail found in British waters. It lives on sandy seabeds where it lays its eggs and uses its long proboscis to feed on other molluscs. Whelks have conical shells, which are often used for shelter by hermit crabs, or found washed up on our beaches.

Black Sea Bream : Spondyliosoma Cantharus

Black Sea Bream

All black sea bream are born female, but they can change their sex once they grow to 30cm long, and any fish over 40cm are male! Black sea bream spawn during April and May. Males build nests where females lay hundreds of thousands of eggs.

Bottlenose Dolphin : Tursiops

Bottlenose Dolphin

Bottlenose dolphins are very intelligent, sociable mammals that travel in small packs and communicate using squeaks and whistles. They can be found swimming in coastal waters all around the UK and can live for up to 50 years.

Common Seal : Phoca Vitulina

Common Seal

The harbour or common seal is both smaller than the grey seal and less prevalent in UK waters. This seal’s blood contains much more haemoglobin than ours, allowing it to stay underwater for around 10 minutes at a time when diving after prey. Seal pups can swim and dive when they are just a few hours old.

Common Sole : Solea Solea

Common Sole

The common or Dover sole is a flat fish that feeds on small worms, molluscs and crustaceans. Both its small eyes are located on the right hand side of its smooth, flat body. In the 19th century, sole was found in abundance in Dover and was considered such a delicacy that special stagecoaches would transport it from Kent to London’s fashionable restaurants.

Cuttlefish : Sepia Officinalis

Cuttlefish

This remarkable creature can change texture and colour either to attract a mate or to help them blend into the background and fool predators. Like its squid and octopus relatives, the cuttlefish is a cephalopod with eight sucker- covered arms and two tentacles. Cuttlefish live in deep water, then move into more shallow areas to mate, and tend to die after they have bred.

Grey Seal : Halichoerus Grypus

Grey Seal

Just under half of the grey seals in the world can be found in British coastal waters. Pups are quite small at birth but put on weight quickly as they develop blubber to help them deal with the cold. Their Latin name means “hook-nosed sea pig”.

Kelp : Laminariales

Kelp

Kelp is the general name for about 30 different types of large seaweed growing along cold coastlines in the Northern Hemisphere. Dried sugar kelp used to be hung up outside to help forecast the weather; if it went soft, it would rain and if it stayed crisp, conditions were likely to remain dry. Giant kelp can grow as tall as 30m, creating thick underwater forests.

Lumpsuckers : Cyclopteridae

Lumpsuckers

As the name suggests, this fish is so chubby that it is almost spherical and has suckers on the underside of its pelvis. Female lumpsuckers lay their eggs near the shore and then swim out to sea, but the males stay with the eggs for more than a month, guarding them from predators until they hatch. Lumpfish roe can be harvested and made into caviar.

Small-spotted Catshark : Scyliorhinus Canicula

Small-spotted Catshark

This small shark is also known as the “lesser-spotted dogfish” or the “rock salmon”, which is how it is listed on fish and chip shop menus.You’ll find it living close to the seabed in shallow waters all around the UK’s coastline. Its egg-casing is nicknamed “the mermaid’s purse”.

Sugar Kelp : Saccharina Latissima

Sugar Kelp

If you have ever ventured onto a British beach, you’ll almost certainly have come across the long, crinkly ribbons of seaweed known as sugar kelp. Sugar kelp grows all around the UK’s coastline and is particularly prevalent in rockpools. It is rich in fibre, vitamins and minerals, and contains the natural sugar mannitol which is used as a low-calorie sweetener and in some medicines.

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