Rye Small Fish Survey 2018

Rye Small Fish Survey

2018

Angharad Purcell and Kathryn Nelson

Sussex IFCA

TABLE OF CONTE

Summary

 Sampling with a seine net was conducted on Rye Harbour beach at 3 hours and 1.5 hours before low tide once per month in May, June and July. Sampling with a survey beam trawl was conducted in September at four stations in Rye Bay.  There was a total of 21 species and a total abundance of 1698.

 Solenette was the most abundant species (29% of total abundance), followed by plaice (25%) and sand goby (21%).  Over half of the plaice (56%) were caught in June and the majority of herring caught in July (63%).

 The average Simpson’s index of diversity was 0.797. The index is a scale of 0 to 1, where 0 represents no diversity and 1 indicates infinite diversity.

 Compared to 2017, in 2018 there were less common and little breeding pairs and fewer fledglings. There were more Sandwich breeding pairs and more fledglings.

 Collaboration was key to the delivery of this project and the hard work and enthusiasm of all those who took part is what made these surveys possible. Thank you to all those who have been involved and supported the surveys.

Introduction The importance of fish The fish populations of the UK, together with the fisheries they support, are of enormous environmental, cultural and socio-economic value. Fish are a major contributor and component of aquatic communities and a key aspect in the majority of marine and estuarine food webs, from consuming microscopic plankton to becoming prey for birds and marine mammals. As such, they play a Brill vital role in ecosystem functioning and are a good general indicator of ecological status and habitat health. Fish can also be used as specific indicators to monitor change in the marine environment for example, temperature and pH (climate change) and water quality (the effects of urban development and pollution).

Small fish The near shore marine and estuarine environments commonly have high productivity and high biodiversity. These zones are home to many small fish species, some of which are adapted to the specific near-shore conditions and remain in-situ for the majority of their life-cycle (e.g. gobies and lesser weevers). Other species utilise the near shore environment during vulnerable stages in their life cycle, for example as ‘nursery’ grounds where the juveniles of larger fish species use the features of the near-shore area for shelter (e.g. sole and herring). Often, these are juveniles of commercially important species and monitoring of the pre-recruitment stock can help inform fisheries management. Turbot

Objectives Integral to effective management is the collection of robust evidence to inform and underpin decisions. The objective of monitoring small fish communities is to develop a time series of biodiversity and relative abundance data in near shore habitats. The information collected will Bass provide data to assist Sussex IFCA in managing sustainable inshore fisheries and support Natural England in the extension of Dungeness, Romney Marsh and Rye Bay Special Protection Area. Specifically, conducting small fish surveys will help:  gain an understanding of the current health of these communities,  provide evidence to guide any actions that may be required to improve the health of these communities,  monitor these communities over time and in relation to any specific or on-going events, and  investigate the ecology of fish species.

Survey locations Rye Harbour is encompassed within two European Marine Sites (EMS); Dungeness Special Area of Conservation (SAC) and Dungeness, Romney Marsh and Rye Bay Special Protection Area (SPA) (Figure 1).

Figure 1: Conservation areas in Rye Bay and surrounding area

The SPA qualifies under Article 4.1 of the Birds Directive (79/409/EEC) by supporting populations of European importance listed in Annex I of the Directive. The Rye harbour section of the SPA has a small shingle beach which supports breeding terns – common tern (Sterna hirundo) and little tern (Sterna albifrons) – and Mediterranean gull (Larus melanocephalus), together with over-wintering wildfowl, including Bewick's swan (Cygnus columbianus bewickii). The area provides valuable feeding habitat for breeding and wintering birds, which feed outside the SPA in nearby shallow waters. Although fish species are not listed as component features for this EMS, they are essential as a primary food source for the Annex 1 breeding populations of common and little terns. Deterioration in fish populations, or a temporal or spatial change in their movements to fall out of sync with the birds’ breeding habits, is likely to cause concomitant declines in the bird species which rely on them as prey, thereby indirectly impacting the features for SPA designation. Data gathered through the Rye small fish survey therefore provides essential evidence to underpin the management needed for the maintenance of SPA features in favourable condition. The data gathered through this ongoing work will also help support work seeking to extend the boundaries of the SPA in order to protect the terns’ foraging range.

Methods

Small fish survey Surveys were conducted once a month in May, June, July and September 2018 following the IFCA Fish Survey Best Practice Guidance. Sampling was only possible when there was settled weather and a calm sea state. A seine net was used (twice in close succession) on Rye Harbour beach at 3 hours and 1.5 hours before low tide in May, June and July. A seine net is a long rectangular net deployed in a semi-circle from the shoreline (Figure 2). The net was deployed by wading by experienced personnel in dry suits. The net was hauled ashore by pulling the float line evenly and keeping it high to prevent fish from jumping over the net, whilst the weighted line was kept as close to the seabed as possible. The contents of the net were shaken down into the centre and transferred into a 40 litre bucket of sea water with an aerator. At each sampling time, the net was redeployed within 5 minutes and within 50m of the first haul.

Figure 2: The seine net used in the surveys; 43m long, 4m wide with a 6.5mm central mesh panel and 14mm mesh in the wings.

In September, a 2m survey beam trawl (Figure 3) was used in Rye Bay. It was deployed from Sussex IFCA’s 18m patrol and research vessel, Watchful. The beam trawl is a long, tapered bag-like net that is held open by a pole or beam. It is towed along the seabed on shoes attached to the ends of the beam. The trawl was towed for ten minutes into the tide at 1-3 knots at 4 survey stations. These survey stations were the same ones used by Cefas for their young fish surveys.

Figure 3: The beam trawl used in the surveys; 2m beam, 7m long net, upper mesh of 14mm and codend of 4mm, 2 tickler chains.

Each sample was kept in a separate bucket of water with an aerator. A hand net was used to move the fish from the bucket to a tray filled with seawater for ease of identification. All fish were identified to species level and the total length (to the nearest millimetre, nose to tail tip) of the first 50 fish of each species was recorded. The remainder were counted. Conspicuous non-fish species were noted. Metadata was recorded and such data included weather, sea state, personnel present, tide time, water temperature, dissolved oxygen, pH and salinity. All data was entered into MS Excel. Analysis was conducted to investigate number of fish species, abundance and Simpson’s index of diversity. Young fish survey data Between 1981 and 2010, the Centre for Environment Fisheries and Aquaculture Science (Cefas) undertook the young fish surveys each year at fixed stations around the south and east coasts of England. As part of a rationalisation of scientific surveys undertaken by Cefas, the YFS was terminated in the southern region in 2006 and in all regions in 2010. Cefas conducted the young fish survey annually in September using a 2m beam trawl towed for ten minutes, covering a distance of 350-600m. The trawl had a 4mm knotless mesh codend, a chain foot-rope and three tickler chains. It was deployed in water depths of 1-25m. All finfish species were measured to the half centimetre below. The abundance of shrimps (Crangon ssp.) was quantified volumetrically and the abundance of epi-benthos was recorded semi-quantitatively. The beam trawl survey stations used in this project were the same ones used by Cefas for their young fish surveys so the data could be compared and the Cefas data could be used to assess the fish populations in the study area in the period 38 to 13 years ago.

Tern breeding data Rye Bay is one of the top sites in the UK for terns. It provides several safe nesting locations and six species of tern have been recorded nesting in the area and a further eight species have also been observed. The three most abundant breeding terns are Sandwich, common and little. The Sandwich tern (Sterna sandvicensis) can be seen in the UK from late March to September and it feeds on fish such as sandeels, sprats and whiting. The common tern (Sterna hirundocan) can be found in the UK from April to September and can forage up to 15km from the breeding colony in search for fish. The little tern (Sterna albifrons) is also a summer visitor and is the smallest UK tern at 21-25cm long. They feed by plunge diving from 1-6m high and submerge for a few seconds up to depths of 50cm. They prefer round fish 5-15cm long but also eat small flat fish, crustaceans and other invertebrates. Results

Small fish survey Nineteen people from seven different organisations were involved in the surveys. This approach of partnership working has been a great part of the surveys and has led to increased shared knowledge, skills and experience. There have also been benefits in the sharing of resources leading to greater cost and time efficiency.

The surveys were conducted during calm weather. This was necessary to allow safe and successful use of the seine net on the open sandy beach near Rye and use of the beam trawl in Rye Bay (Figure 4).

Figure 4: Location of the Rye survey sites; seine netting on the beach and survey beam trawling at 4 stations in Rye Bay. Seine net sampling took place in May, June and July on Rye Harbour beach during neap tides with a low tide time between 14:00 and 16:00 and height of 1.5-1.8m. The first neap tide of the month was selected as first choice and the second neap tide as a backup date if the weather was not suitable on the first. The surveys were conducted during calm weather. The beam trawl survey took place on the 4th September, with a low tide time of 12:29 and height 2.0m. Physical parameters The highest water temperature for an individual sample was in July (21.2oC) with the daily average water temperature of 20.7oC whereas in June it was 17.7 oC. The lowest water temperature was in May (14.0oC). Across the summer the average salinity was 34.8 psu (35 psu is fully saline seawater) and varied 0.4 psu. The average pH was 8.1 and varied by only 0.3. The average dissolved oxygen was 7.7 mg/l ± 2.6. During September’s beam trawl survey, the average water temperature was 18.6oC and salinity 35.05 psu. Average pH was 8.14 and dissolved oxygen 7.92 mg/l. Fish In total, there were 1698 fish from 21 species (Figure 5). The three most abundant species were solenette (29%), plaice (25%) and sand goby (21%). The vast majority of solenette (97%) and sand goby (99%) were caught in September during the beam trawl survey, whereas only 3% of the plaice were caught in the beam trawl. The majority of plaice (56%) were caught in June and the majority of herring were caught in July (63%).

Relative abundance 0% 5% 10% 15% 20% 25% 30% 35%

Solenette May Plaice June Goby - Sand July Herring September Weever - Lesser

Sprat

Sole - Dover

Flounder Greater pipefish Sole - Sand

Pipefish - Lesser Plaice

Bass Species Goby - Common Solenette Dragonet - Reticulated

Mullet - Thin Lipped Sprat

Tub Gurnard

Brill Bass

Goby - Transparent

Thornback Ray

Turbot

Pipefish - Greater Thornback ray Lesser pipefish Goby - Juvenile

Figure 5: The relative abundance of the 21 species caught using seine net May, June, July and beam trawl in September 2018.

In previous years the most abundant species were solenette 2017 (28%), sprat 2016 (35%), herring 2015 (33%), bass 2014 (20%) and herring 2013 (79%).

The Simpson’s index of diversity was used to assess the number of species and the evenness of distribution of abundance across those species. The index is a scale of 0 to 1, where 0 represents no diversity and 1 indicates infinite diversity. Overall (including data from beam trawl and seine net surveys), the annual average Simpson’s index of diversity for 2018 was 0.797. This is slightly lower than 2016 (0.827) when both beam trawl and seine net surveys were last conducted because the 2018 samples were more heavily dominated by Solenette (52%) and sand goby (37%).

The beam trawl survey in September had the highest abundance (933) with 12 different species. June had the next highest abundance (353) with the same number of species (11) as July. May had the lowest abundance (154) and the least number of species (9).

From the seine net survey data, the most abundant species in 2018 was plaice (55% 421), followed by herring (14% 103), lesser weever (11% 82) and sprat (10% 79) (Figure 6). The majority of plaice (58%) were caught in June and herring (63%) caught in July. All sprat (100%) were found in July. 49% of the lesser weever fish were caught in May, with 34% in June and 17% in July. The seine net survey data gives the average Simpson’s index of diversity at 0.656.

Data from all seine netting survey months were combined to elucidate differences in samples collected at different states of the tides.

The samples collected at 1.5 hours before low tide had a greater average number of species (6.5) compared to the sample collected at 3 hours before low tide (3.83) with the LW-1.5 sample also having a greater average abundance (95) than the LW-3 sample (32).

The LW-1.5 sample had a slightly lower average index of diversity (0.517) than LW-3 sample (0.536).

Relative abundance 0% 10% 20% 30% 40% 50% 60%

Plaice May Herring June Weever - Lesser July Sprat Flounder Solenette Thin lipped mullet Common goby Bass Sole - Dover Goby - Common

Species Goby - Sand Mullet - Thin Lipped Pipefish - Lesser Brill Turbot Lesser weever Goby - Transparent Thornback Ray Turbot Pipefish - Greater

Figure 6: The relative abundance of the 17 species caught using seine net in 2018 in May, June and July.

The average index of diversity was 0.656. The highest diversity was in July (0.744) and the lowest diversity was in June (0.502) as more than half of the total catch was plaice (55%).

Conspicuous non-fish species included swimming crabs, shore crabs, hermit crabs, shrimps, sea gooseberries (ctenophores), moon jellyfish, and various seaweeds.

Comparison with other sites Sussex IFCA also conducts small fish surveys in Medmerry managed realignment (near Selsey) and Chichester Harbour (on the border between West Sussex and Hampshire) using a combination of seine nets and fyke nets. Direct comparison of these surveys is difficult due to the different methods, sites and habitats. However, it can still be useful to put the Rye survey in context. In 2018, there were 14 species in Medmerry and 9 in Chichester Harbour. The average index of diversity was 0.755 in Medmerry and 0.393 in Chichester Harbour. In comparison, Rye had 23 species and the average diversity was 0.836, both parameters greater than the other sites in Sussex.

Plaice There was a total of 432 plaice from seine and beam net surveys combined, 25% of total overall abundance. A total of 280 plaice were measured; 269 from the seine net surveys and all plaice caught in the beam trawl (11) in September. They measured between 18mm and 325mm.

Looking at the seine net data, the plaice were smaller (18 – 42 mm) in May than in June (20 – 64 mm with one fish at 182 mm not included in the graph) and July (32 – 75 mm with one fish at 110 mm not included in the graph), showing their growth rate across the summer (Figure 7). There was less abundance in July (19%) compared with May (23%) and June (58%). In May the lower abundance could be due to the plaice spawning season being January to March and in May some of the plaice would have been too small to be caught in the seine net. The round-fish larvae are surface dwelling for 4-6 weeks then they become bottom dwelling flat fish at 10-17 mm.

5% May 4% June

4% July

2% Relative Relative abundance

0% 18 23 28 33 38 43 48 53 58 63 68 73 Length (mm) Figure 7: The length frequency of plaice in May, June and July 2018.

Herring and sprat There was a total of 103 herring (14% of the total abundance) all caught during the seine net surveys. 63% of the herring were caught in July with the remaining 37% in June. They were 40-70 mm long with an average length of 48 mm (Figure 8). Herring form distinct spawning stocks with individual spawning grounds and season. In Sussex, herring are believed to spawn in February and they grow to a maximum of 450 mm long. There was a total of 79 sprat (10% of total abundance) all of which were found in July. The sprat were 35-57 mm long with an average length of 42 mm (Figure 8).

70% Herring 60% Sprat

50%

40%

30%

20%

Relative Relative Abundance 10%

0% 31-40 41-50 51-60 61-70 Length (mm)

Figure 8: The length frequency of herring and sprat

Solenette There was a total of 497 solenette, 29% of the total abundance. 97% of the solenette were caught in the September beam trawl survey with the remaining 3% in June and July. This is the second year (following 2017) where solenette is the most abundant species. They were between 23mm and 92mm long (Figure 9). This is the smallest member of the sole family and can reach a maximum length of 130mm. It is common in sandy habitats down to depths of 40m. They have regular black lines on their dorsal and anal fins which helps distinguish them from other similar juvenile flat fish.

80%

70%

60%

50%

40%

30% Relative Relative Abundance 20%

10%

0% 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 Length (mm)

Figure 9: The length frequency of solenette

Young fish survey

Sandeels Sandeels, herring and sprat are important prey species for many marine birds. This project was particularly interested in the availability of small round fish as a food source for breeding terns. Across all years (1981-2006) and all stations in the south coast region, there were only 150 sandeels (Ammodytes tobianus and Hyperoplus lanceolatus). 89% were the lesser sandeel (Ammodytes tobianus). There was an average of 0.04 sandeels per station. There were not enough sandeels to draw any statistically robust conclusions. The Rye small fish survey found no sandeels in 2016 - 2018 or 2014, just one in 2015 (in the seine net) and two in 2013.

Herring and Sprat Herring and sprat are considered to be an important food source for breeding terns and juveniles often form mixed shoals. There was an average of 0.87 herring per station and an average of 0.07 sprat per station across all south coast stations and all years. This was 22 times as many herring and twice as many sprat per station compared to sandeels. The abundance of herring increased from the early 1980’s to late 2000’s with a dip in the early 2000’s. The abundance of sprat has also increased and became more abundant than herring in the early 2000’s (Figure 10).

In 2018, Rye small fish survey found no sprat or herring in the beam trawl, as was the case in 2016. In 2014, there were 5.00 herring and 3.56 sprat per station, as well as a remarkable 583.78 juvenile herring/sprat per station. In 2013, there were 9.09 herring/sprat per station. No beam trawling took place in 2017 or 2015.

0.40

0.30

Herring 0.20 Sprat

0.10 Abundanceper station 0.00

Year class

Figure 10: The annual average abundance of herring and sprat per station from all south coast stations per year class.

Gobies Gobies (all species combined) were the most abundant taxa in the Cefas surveys. They are in the size range of fish preferred by terns (average length 48mm) although they are generally a benthic species and may not be easily available for terns. There was an average of 40.84 gobies per station across all south coast stations and all years. This was 47 times more abundant than herring, over 580 times more abundant than sprat and over 1000 times more abundant than sandeels. The abundance of gobies has increased from the early 1980’s to the late 2000’s (Figure 11). The average abundance per station was similar in the nine stations in Rye bay and off Hastings (41.25). In 2018, there was an average of 87 gobies per station.

Abundanceper station

Year class

Figure 11: The annual average abundance of gobies (all species combined) per station from all south coast stations per year class.

Tern breeding data Rye Bay is one of the top sites in the UK for terns. Common, Sandwich and little terns all nest within the Dungeness, Romney Marsh and Rye Bay SPA. All are listed as qualifying species under Article 4.1 of the Birds Directive (2009/147/EC).

Sandwich terns There was an average of 147 pairs of Sandwich terns per year between 1970 and 2018. The number of breeding Sandwich terns increased from the mid-1980s until a peak of 850 breeding pairs in 2011. There was an average of 96 fledglings per year with a maximum of 1000 in 2010 (Figure 12).

1000 900 800 Pairs 700 Fledglings 600 500

400 Abundance 300 200 100 0

Year

Figure 12: The number of pairs and fledglings of sandwich terns between 1970 and 2018.

There was on average 0.3 fledglings per pair with a maximum of 1.6 in 2003. Between 1970 and 2018, there were 18 years with no pairs and 27 years with no fledglings. In 2018, there were 320 pairs of Sandwich terns, less than the 2011-2017 average (399) but greater than the 1970- 2017 average (143). There were 91 fledglings which was greater than the 2011-2017 average (36) but less than the 1970-2017 average (97).

Common terns There was an average of 88 pairs of common terns per year between 1970 and 2018. The number of breeding common terns increased from the early 1970s until a peak of 341 breeding pairs in 2010. There was an average of 70 fledglings per year with a maximum of 500 in 2010 (Figure 13). There was on average 0.7 fledglings per pair with a maximum of 2.3 in 1995. Between 1970 and 2018, there were 3 years with no pairs and 6 years with no fledglings. In 2018, there were 110 pairs of common terns, greater than the 2011-2017 average (142) and the 1970-2017 average (88). There was just 1 fledgling, lower than the 2011-2017 average (29) and below the 1970-2017 average (72).

500 450

400 Pairs 350 Fledglings 300 250

200 Abundance 150 100 50 0

Year Figure 13: The number of pairs and fledglings of common terns between 1970 and 2018.

Little terns There was an average of 26 pairs of little terns per year between 1970 and 2018. The number of breeding little terns increased from the late 1970s until a peak of 76 breeding pairs in 1985 and then numbers declined. There was an average of 12 fledglings per year with a maximum of 60 in 1987 (Figure 14). There was on average 0.5 fledglings per pair with a maximum of 2.0 in 1975 and 1976. Between 1970 and 2017, there were 3 years with no pairs and 11 years with no fledglings. In 2018, there were 12 pairs of little terns, the same as the 2011-2017 average (12) but below the 1970-2017 average (27). There were no sightings of fledglings this year; the first year with no fledglings since 2012.

70 Pairs 60 Fledglings 50

30 Abundance 20

Year

Figure 14: The number of pairs and fledglings of little terns between 1970 and 2018.

Acknowledgments Collaboration was key to the delivery of this project and the hard work and enthusiasm of all those who took part is what made these surveys possible. The sharing of skills, knowledge, experience and resources through partnership working has also been instrumental to the success of the surveys, increasing efficiency, productivity and proficiency. This project would not have been possible without the collaboration between Rye Harbour Nature Reserve (Sussex Wildlife Trust) and Sussex IFCA, with the support of volunteers from the Environment Agency, Natural England, the Institute of Fisheries Management and the University of Brighton. With budget constraints across many organisations, working together has clear benefits for increasing efficiency and maximising resources. It will take several years to build up a robust dataset at Rye to give a strong picture of the composition and trends in the small fish population. Thank you to all those who have been involved and supported the surveys.

Key findings  There was a total of 21 fish species and a total abundance of 1698.  Solenette was the most abundant species (29% of total abundance), followed by plaice (25%) and sand goby (21%).  The average Simpson’s index of diversity was 0.797. The index is a scale of 0 to 1, where 0 represents no diversity and 1 indicates infinite diversity.

 There was a wide diversity of conspicuous non-fish species.

 There were 320 breeding pairs of Sandwich terns with 91 fledglings. There were 110 pairs of common terns with just one fledgling. There were just 12 pairs of little terns with no observed fledglings.

 The surveys involved 18 people from 7 organisations.