Fish survey helps understand the ecology of Allonby Bay HPMA

Summary

In 2024, we conducted a series of non-destructive fish surveys in the newly designated Allonby Bay Highly Protected Marine Area (HPMA), located on the Solway Firth in Cumbria. These surveys, commissioned by Natural England, aim to establish a baseline understanding of the diverse fish assemblages within this ecologically significant site. Using innovative, low-impact methods, such as long lines, fish traps, and fyke nets, the team has already identified a range of species, including thornback rays and shark species like bull huss. The findings will contribute to long-term monitoring efforts, guiding conservation strategies and ensuring the protection and recovery of this unique marine ecosystem.

Background

Allonby Bay is a crescent shaped bay on the Solway Firth north of Maryport in Cumbria. In June 2023, it was designated a Highly Protected Marine Area (HPMA) and is currently one of only three HPMAs established around the UK and the only one within 12 nautical miles of the shore.

It extends approximately 5.6km seaward and covers an area of 27.6km² at high water. It sits within both the Allonby Bay Marine Conservation Zone (MCZ) and the Solway Firth Special Protection Area (SPA).

The seabed has a range of rocky and sediment-dominated habitats that provide spawning grounds for sole, thornback ray and bass and nursery areas for cod, herring, plaice, sole and thornback ray. In turn, these fish species attract diving, foraging seabirds, including guillemots, gannets and razorbills and important migratory, non-breeding bird species. The mussel beds and intertidal pools also attract large densities of shore birds, including curlews and oystercatchers (see link below).

The area is prone to dramatic currents and tides.

One of the best examples of honeycomb worm reefs in the UK is found here, providing habitats for crabs, molluscs and other species. The honeycomb reefs and blue mussel beds can also provide both water purification and important coastal erosion protection.

HPMAs take a ‘whole site’ approach, so the entire marine ecosystem within the HPMA is designated for a high level of protection. Management measures are being established to ensure that extractive, destructive and depositional uses do not prevent the ecosystem from recovering to its natural state.

The project

Surveys of the entire marine ecosystem were commissioned by our client, Natural England, and delivered through partnerships, contracts or in house by Natural England. The work being undertaken by Ocean Ecology is focused on understanding fish assemblage throughout the area.

The first baseline survey was carried out in March 2024. A summer survey monitoring the area was carried out in August-September, followed by an autumn survey in October-November. A winter survey was scheduled to be carried out in January 2025. Long-term monitoring will also form part of the project, although this work has not yet been commissioned. A control site further down the coast and outside of the HPMA provides scope for comparison.

The approach to the surveys is exacting and the methods we are able to use are highly restricted and non-destructive. That includes non-destructive fishing methods, so no beam trawl or gill nets are used.

Working with ‘non-destructive’ restrictions

“High levels of animal husbandry are required when measuring length and biomass of fish,” explained Ocean Ecology project manager Lucy Martin.

“We work extremely quickly with a deck full of buckets of fish with aerators bubbling away to replenish oxygen levels. The materials used for nets and weighing bags have been chosen to be non-abrasive.

“We handle the fish carefully following the Standard Operating Procedures determined for the project, such as how to remove hooks, being careful of fins on nets and not putting fingers near gill plate covers. Our surveyors are well-trained and experienced and already have the skill sets required for this.

“We even substituted our heavy-duty gloves when handling some species because nitrile gloves can be better for fish protection – they’re less abrasive to fish scales.”

Public perception of the work is also a sensitive matter and has to be taken into consideration.

“We use long lines, fish traps, fyke nets, beach seines and beach-seine tows as well as conducting searches in rock pools,” added Lucy.

“In the first survey, we found a lot of shark species including bull huss (Scyliorhinus stellaris) up to 1m long and 4.5kg. And we’ve found plenty of thornback rays (Raja clavata) including one laying an egg case. We are interested in catching all size classes to see the different ages present.

“It’s obviously a very special site – hence the level of protection it’s been given – but the restrictions that it presents in the way we work have made it even more interesting.

“And while, on this project, we are not collecting or analysing samples in our own eDNA lab, we will incorporate our client’s results from their eDNA surveys here into our data analysis and reporting. It all adds to our experience as we develop eDNA analysis as an important strand of our business.”

Reports on each survey are written after completion and provided to the client. Our fish surveys form part of a wider environmental and ecological analysis which, along with further monitoring, will enable progress towards the conservation objective to be evaluated and help to assess the impact of any developments in the wider area and onshore.