Field Guide to Juvenile Fish of the Tidal Thames

Field Guide to Juvenile Fish of the Tidal Thames January 2017 Thames Conservation Programme Zoological Society of London Regent's Park London, NW1 4RY marineandfreshwater@zsl.org

Introduction The Tidal Thames is a highly productive estuarine system. In recent years, 125 species have been recorded. In particular, the Tidal Thames is an important spawning habitat, rich foraging ground and allows migratory fish to move between saltwater and freshwater (and vice versa). This Guide was developed as part of a wider project focusing on Fish Conservation in the Tidal Thames. More information relating to fish conservation planning in the region can be found in the recently published Guidance Document: Conservation of Tidal Thames Fish through the Planning Process. This guide has been produced to help with the identification of larval and juvenile developmental stages of fish in the Tidal Thames. Larval stage is defined as the stage hatching. Recently hatched larvae will have a yolk sac which will feed the larvae. The yolk sac will be absorbed for several days until they are able to feed on live prey. When fish reach juvenile stage, they usually resemble to small adults. This stage will end once they are sexually mature (FinFish Hatchery, Seagrant MIT). The species listed are most commonly found in the Tidal Thames in Greater London, however this guide can be more widely used to inform fish identification in estuarine waters around the UK. It has been designed to enable conservation practitioners, scientists, consultants and citizen scientists to better identify Early Life History Stage (ELHS) fish (i.e. larval and juvenile fish) in the field, where taking samples for observation under a microscope is not possible. 2

Acknowledgments This project was led by the Zoological Society of London as part of the Marine and Freshwater Conservation Programme. It was made possible with thanks to funding from the Heritage Lottery Fund (HLF). We are very grateful for the help of Steve Colclough from the Institute of Fisheries Management (IFM) and Tom Cousins and Peter Gray from the Environment Agency (EA) who provided advice on which species to include and their identification in this guide. Additional thanks go to Jamie Craggs, Andy D. Nunn, Neil Garrick-Maidment, Gareth Jones, Pete Liptrop, John Newman, Paul Peters, Adrian Pinder, David Powell and Katherine Tye who provided invaluable photos and expertise of various species to use in this Guide. The Pocket Guide to Freshwater Fish of ritain and Europe by Malcolm Greenhalgh (2001), Keys to Larval and Juvenile Stages of Coarse Fishes from Fresh Waters In The ritish Isles by Adrian C. Pinder (2001) and Key To Marine and Freshwater Fishes of ritain and Ireland by Peter S. Maitland and Douglas Herdson (2009) were used as key reference material to develop this Guide. All the photos are credited as appropriate, except for those taken by ZSL staff. If you have any comments or suggestions on this Guide, please get in contact with us at marineandfreshwater@zsl.org. We would like to make this Guide a live document, and update it with new relevant details. 3

How to use the guide Photos of each species accompany descriptions of features that can be observed in the field. esides the physical attributes of each fish, the most likely location and seasonality for each species is also described. It is important to note that the Tidal Thames is a dynamic system and that the details regarding where and when the species can be found should be taken as a guidance and might not always apply. Seasonality A calendar on each page identifies the most likely months where the ELHS fish can be found. The timings are divided into four groups : A: January to March C: July to September A : April to June D: October to December Location The map for each species shows the most likely location in the Tidal Thames during ELHS. The Tidal Thames has been divided into three sections to aid interpretation: L1: Upper Thames, from Teddington to Wandsworth L2: Middle Thames, from Wandsworth to the O2 L3: East of the Thames, from the O2 to Gravesend Some species might be found in more than one zone; if this is the case the map is extended to show this (see below). L1 L2 L3 L1 & L2 & L3 L1 & L2 L2 & L3 L3 & outside 4

Type of protection Some of the species will have a box indicating the category of the species. This might be either Protected or Infrequently found. The "Infrequently found" species are the ones less likely to be found in the Tidal Thames; "Protected" species are listed on one of the following regulations: PROTECTED INFREQUENTLY FOUND Wildlife and Countryside Act (WCA) NERC Species of Principal Importance (NERC) MCZ Species Features of Conservation Importance (MCZ) London AP Priority Species (L-AP) UK AP Priority Species (UK-AP) ern Convention Protected Fauna (CPF) Habitats Directive (HD) Fish anatomy Throughout the guide specific vocabulary will be used to refer to the fish anatomy. It is important to know the name of these body parts to allow accurate identification. The physical attributes of each species are organised from the easiest to observe to the least. Some attributes are essential for the ID of a species. These are followed by ** and * (with ** showing a higher importance than *). 1. First dorsal fin 2. Second dorsal fin 3. Tail or Caudal fin 4. Head and gill cover 5. Pectoral fins 6. Pelvic fins 7. Anal fin 8. Adipose fin 9. Melanophores 10. Tail wrist It is also important to know how to differentiate the different tail shapes to correctly ID on individual. In this guide we describe three main Convex Straight Concave tail shapes. 5

Identification tips There are some things that should be taken into account when ID-ing fish. Here are some tips that will help during the ID on site as well as the one done afterwards, when looking at all the data and photos gathered. How to identify a species Look at the tip of the mouth to ID a fish. Look for the lines of melanophores when very young. Look at the shape of the tail and fins Look at the body shape Use a hand-magnifying glass when available.. Take photos from the side. What to do if you can t ID If you are unable to ID the fish, take some good pictures of the whole fish, with fins extended (and if possible mouth open) and send them to ZSL or another expert. When in doubt, report it as not known. If possible, it would be good if an Fish ID expert could have a quick look at your tray, just in case he can spot an odd one among the whole group. How to take an ID photograph Try to have enough water covering the fish, so that it can swim and be seen clearly. Make sure that when taking a picture there is no shade over part of the fish. The photos made through plastic have a lower quality. If possible, use a glass vessel. Important to have all the fins extended when taking the photo. Important to report the time and location of where the fish was found. Important to always scale the fish to know its size any object can be used for scaling, but preferably a ruler. 6

Atlantic Cod (Gadus morhua) PROTECTED (NERC & UK-AP) A 1** 2* Patrick Gijsbers,C,D 1. Three dorsal fins** 2. Very pronounced chin barbel * Not to be confused with : A. Sandy brown/greenish colour. Separation between fins Whiting 7

Atlantic Salmon (Salmo salar) PROTECTED (NERC, CPF, HD & UK-AP) 4 1* 3 Ribble Rivers Trust A Ribble Rivers Trust Not to be confused with : rown trout A,, D 1. Adipose fin* 2. Mouth almost faces upwards 3. Thin tail-wrist 4. Tail fin has a pronounced edge A. Jaw is shorter than trout. Pelvic fin is long Ribble Rivers Trust 8

arbel (arbus barbus) PROTECTED (HD) INFREQUENTLY FOUND Piet Spaans 1* Andy D. Nunn 1* Where and when could you find it?,c 1. Two pairs of barbels on the upper lip* A. Rich brown-olive colour. High dorsal fin but short base 9

ullhead (Cottus gobio) PROTECTED (HD) 1 1 Hans Hillewaert 2 2 Not to be confused with : C & D Common goby 1. Flat head 2. Two dorsal fins linked together: no gap in between A. Same as larvae. Small fish (adults: 10 cm maximum length) 10

rown/sea Trout (Salmo trutta) PROTECTED (NERC, L-AP & UK-AP) 2 1* 3 4 Andy D. Nunn A C Ribble Rivers Trust Not to be confused with : A,, D 1. Adipose fin* 2. Head has a round shape 3. Thick tail-wrist 4. Tail fin has a less pronounced edge than Salmon Atlantic salmon A. Silvery colour. Jaw extends to back of the eye Gareth Jones C. Pelvic fin is short 11

Chub (Leuciscus cephalus) 3 1* 2 1* Andy D. Nunn Ribble Rivers Trust A* 2 C Ribble Rivers Trust,C 1. Convex anal fin* 2. Smaller mouth than Dace & Roach 3. Pigmentation around head Not to be confused with : Dace A. Dorsal fin is placed just behind pectoral fins **. Pelvic and pectoral fin lightly orange darker in colour than Dace)* 12

Common ream (Abramis brama) Juvenile Fish ID Guide for the Field 3 3 2 1* D E A A C could find it: Not to be confused with:,c,d Dace 1. Long anal fin * 2. Deep in body, but in the very young ones it might be hard to see 3. No pigmentation in the eye A. Long anal fin *. Mouth extends into feeding tube C. Green-silvery body D. Clear and large eye E. Hump-shaped 13

Common Goby (Pomatoschistus microps) PROTECTED (CPF) 1** 1** David Curnick 2* A* David Curnick Not to be confused with:,c,d 1. Prominent eyes that protrude from the head** 2. lack mark on root of pectoral fin* 3. If you turn them over: see pectoral fins are attached to the body at the base of the fin. Yuriy Kvach Sand goby A. Prominent eyes that protrude off the head*. More dark coloured than Sand gobies 14

Dace (Leuciscus leuciscus) 3 D A* C 2 1* 1* Not to be confused with: ass Chub,C,D ream 1. Concave anal fins * 2. Thick lateral line 3. igger mouth than eye A. Pectoral and pelvic fins: translucent, yellow*. Eye high up in the head C. No colour in the eye D. Silvery, slightly green on top Environment Agency 15

Dover Sole (Solea solea) PROTECTED (NERC & UK-AP) Environment Agency 1 3 2 A David Curnick Not to be confused with :,C,D 1. Flatfish 2. Very small pectoral fin 3. Elongated shape A. rownish colour. Long fins (almost to back of the tail) Flounder and other flatfishes 16

European Eel (Anguilla anguilla) PROTECTED (NERC, L-AP & UK-AP) 1, C A,C,D 1. Glass eel stage: Transparent. Not to be confused with : A. Yellow eel stage: rown above, yellowish below and on the sides.. Protruding lower jaw C. Small teeth Lampreys 17

European Smelt (Osmerus eperlanus) PROTECTED (NERC, MCZ, L-AP & UK-AP) 2* 3 1** 4 A A* C*,C,D Not to be confused with: Dave Powell 1. Adipose fin** 2. Huge eye* 3. No melanophores - transparent body 4. lackness in caudal fin 5. Smells like cucumber* A. Melanophores in tail fin **. Pinkish colour Sand smelt C. Predator mouth* 18

Sprat (Sprattus sprattus) Hans Hillewaert 2 1 3 could find it: Not to be confused with: Herring A,C,D 1. Rough surface on the lower part of the body 2. Front end of pelvic fin in front of dorsal fin 3. Up-turned mouth A. Small fish (adults: less than 16cm). Silver colour, greenish on the back 19

Flounder (Platichthys flesus) Juvenile Fish ID Guide for the Field 5 2* 1** 4 3 Not to be confused with: Plaice, other flatfish,c Larvae and juvenile characteristics 1. If you run your fingers on the edge of the fish, you will feel that is covered in prickles (rough area)** 2. Straight tail (not convex as Plaice)* 3. Flat fish - no other flatfish penetrates in low salinity (normally) 4. Long body shape 5. It usually has no orange spots on its back 20

Grayling (Thymallus thymallus) PROTECTED (CPF, HD) 1* 2 Andy D. Nunn A* C Liondelyon,C,D 1. Adipose fin * 2. Flattened bottom - lives in fast water A. Huge dorsal fin*. Small eye compared to the body size C. Long shallow jaw 21

Perch (Perca fluviatilis) 2 3 5 1* 4 A* could you find it: Not to be confused with: ass, C, D 1. Melanophores do not appear on the edge of the fish, but inside it * 2. Green-ish (in top of the head) in colour 3. Top of the head slightly faces down (less aquadynamic-look than bass) 4. Large predator eyes 5. lackness in caudal fin A. lack-bars banding across the body-not always obvious *. Double dorsal fin, with shallow separation Ribble Rivers Trust 22

Pike (Esox lucius) INFREQUENTLY FOUND 1 2* 3 Andy D. Nunn A C Andy D. Nunn C, D 1. Elongated body shape 2. lack stripe of pigment below the eye* 3. Already predator-like mouth, still hard to identify at this stage A. Green silvery on top. Dorsal fins are very far back C. Very predator-like look 23

Plaice (Pleuronectes platessa) PROTECTED (NERC, UK-AP) D** A C * D** Arnstein Rønning Where and when could you find it? Not to be confused with: A,, C Flounder A. Rounder body-shape than the Flounder. Tail is convex* C. Deeper in body D. No prickly feeling (see Flounder description): 100% smooth body, when you run your fingers on the edges of the fish** E. Has orange spots on the top side 24

Pouting (Trisopterus luscus) Juvenile Fish ID Guide for the Field C A** D A,D * Larvae and juvenile characteristics A. Three dorsal fins, the first of which is high and triangular **. One single barbule, on chin * C. ack is usually brownish to orangey/copper in colour and underbelly is pale. D. Thick stripes can sometimes be found running down the flanks of this species, although not always present 25

River Lamprey (Lampetra fluviatilis) PROTECTED (NERC, CPF, HD, L-AP & UK-AP) 2* 4 3 1** C-D Larvae & juvenile characteristics 1. Sucker disk with tooth plates and small teeth** 2. 2 fins* Not to be confused with : European eel 3. Looks like a small adult eel 4. right silver colour 5. It's smooth to the touch* Note : Please, send us a photo via email to : marineandfreshwater@zsl.org 26

Roach (Rutilus rutilus) 1* 2 Lauren Vickers 1* C A could find it:,c,d 1. Red/Orange eye* - at least a hint of colour 2. Mouth never bigger than eye Not to be confused with: Dace A. Pelvic and anal fins are orange-red. Less deep in the body, and broader than ream C. Hint of blue on the back/lateral line 27

Sea ass (Dicentrarchus labrax) Juvenile Fish ID Guide for the Field 2* 3 4 1** 5 2* A could find it: Not to be confused with: Perch Dace,C,D 1. Dark edging of fish ** 2. Two dorsal fins* 3. Line in ventral body 4. Purple-pink colour on lower part of the head, and hint of orange on top. 5. Thick head and large mouth at the end A. Dark edging disappears. Lighter colour than perch 28

Sand Goby (Pomatoschistus minutus) PROTECTED (CPF) 3 2** Yuriy Kvach 1* Where and when could you find it? Not to be confused with: Common goby,c Larvae and juvenile characteristics 1. If you turn them over: Pectoral fins look separated from the body, like two small arms* 2. Eyes don't stick out of the head ** 3. Sand colouration (pink sand) David Curnick 29

Sand Smelt (Atherina presbyter) Juvenile Fish ID Guide for the Field 1 2 Citron / CC Y-SA 3.0 A Dave Powell, C, D 1. Two dorsal fins 2. No predator-like mouth Not to be confused with : European smelt A. Similar to herring, with a clear black line. Pelvic fin has a V-shape Herring 30

Short-snouted Seahorse (Hippocampus hippocampus) PROTECTED (WCA, NERC, CPF, MCZ, UK-AP) 3 John Newman 2 1 Not to be confused with : Spiny seahorse Neil Garrick-Maidment, C, D Larvae and juvenile characteristics 1. Seahorse body form 2. rown colour 3. Short-snout (under 1/3 of the head length) Note: The Short-snouted seahorse is the most likely seen right up the Thames. Hard to differentiate. est recommendation is to take one or several good photos and put the animal back in the water. They are very fragile. 31

Spiny Seahorse (Hippocampus guttulatus) PROTECTED (WCA, NERC, MCZ, UK-AP) INFREQUENTLY FOUND 3 Neil Garrick-Maidment 2 1 Neil Garrick-Maidment, C, D Larvae and juvenile characteristics 1. Seahorse body form 2. ody rings with spines on the angles Not to be confused with : Short-snouted seahorse John Newman 3. More delicate looking than long-snouted seahorse Note: Again, hard to differentiate. Take one or several good photos and put the animal back in the water. They are very fragile. (Photo on the left shows a pregnant female) 32

3-spined Stickleback (Gasterosteus aculeatus) 1* A * Ribble Rivers Trust,C,D 1. Spines on the back: two very obvious and one tiny * A. Same shape as juveniles.. Males turn blue and red during spawning season * 33

Stone Loach (arbatula barbatula) INFREQUENTLY FOUND D C Andy D. Nunn A* Ribble Rivers Trust A,,C,D Larvae and juvenile characteristics A. Six long barbels*. Flattened tail C. Slender body D. Green-brown above, hint of yellow on the sides E. Small fish (adults: not bigger than 15 cm) 34

Thin-lipped Grey Mullet (Liza ramada) Juvenile Fish ID Guide for the Field 2 1* A* C Where and when could you find it?,c 1. Under 15 mm: they have no scales yet, and they develop an iridescence 2. Large eye compared to the size of the body Not to be confused with: Roberto Pillon Thick-lipped grey mullet A. Two dorsal fins *. Presence of a characteristic spot behind the pectoral fin C. Pectoral fin when turned reaches back of the eye 35

Twaite Shad (Alosa fallax) PROTECTED (WCA, NERC, CPF, L-AP & UK-AP) A 1 could find it:, C, D 1. Deeper in the body than herring Note: Hard to distinguish from herring under 5 cm. Not to be confused with : Herring A. Strange eye shape. lack spots on the side Note: Schools with Herring and Sprat sometimes 36

Whiting (Merlangius merlangus) PROTECTED (NERC & UK- AP) 3 2 1 A C, C, D 1. Spot over pectoral fin 2. Small barbel 3. Three dorsal fins Not to be confused with : Atlantic cod A. Pale body: pinkish on the surface and underneath. Two anal fins C. Concave tail fin 37

Zander (Sander lucioperca) 2* 1 3 Andy D. Nunn A Andy D. Nunn Where and when could you find it? Not to be confused with: European smelt,c 1. Long-thin head 2. Two dorsal fins * 3. Clear tail A. Two dorsal fins. Elongated shape of the head Note: This is an invasive species 38

Appendix: Fish Larvae Lengths Common name Species name Larvae maximum length (mm) Atlantic cod Gadus morhua 20 Atlantic salmon Salmo salar 24-29 arbel arbus barbus 12.5-22 ullhead Cottus gobio 7.5-8.5 rown/sea trout Salmo trutta 25 Chub Leuciscus cephalus 14-17 Common bream Abramis brama Dec-15 Dace Leuciscus leuciscus 13-17 Common goby Pomatoschistus microps 11-12 Dover sole Solea solea 7-10 European eel Anguilla anguilla 120 European plaice Pleuronectes platessa 13-14 Sea ass Dicentrarchus labrax 23-25 European smelt Osmerus eperlanus 21.6 European sprat Sprattus sprattus 25-28 Flounder Platichtys flesus 8-20 Grayling Thymallus thymallus <30 Perch Perca fluviatilis 11-21 Pike Esox lucius 19-26 Pouting Trisopterus luscus 48-50 River lamprey Lampetra fluviatilis 80-120 Roach Rutilus rutilus 11.5-17 Sand goby Pomatoschistus minutus 12 Sand smelt Atherina presbyter 20 Short-snouted seahorse Hippocampus hippocampus 30-40 3-spined stickleback Gasterosteus aculeatus 14-15 Spiny seahorse Hippocampus guttulatus 30-40 Stone loach arbatula barbatula 15-18 Thin-lipped grey mullet Liza ramada <10 Twaite shad Alossa fallax 13-15 Whiting Merlangius merlangus 14 Zander Sander lucioperca 13-23 39