Weever fish What the non-commercially exploited species can tell us about climate change Richard...

Weever fish

What the non-commercially exploited species can tell us about climate change

Richard D.M. Nash1, Audrey J.Geffen1,2 & Henk Heessen3

1. Port Erin Marine Laboratory, University of Liverpool, Isle of Man, British Isles2. Department of Biology, University of Bergen, Norway3 Netherlands Institute for Fisheries Research, IJmuiden, The Netherlands

Why have an interest in non-commercial species?

However, changes in population size may be a consequence of fishing operations due to changes in habitat, ecosystem status and/or predator/prey relationships.

Therefore one cannot just choose any species if one wants to try and look at possible effects of climate change on fish populations and areas.

Changes in population size are not directly driven by commercial fishing.

The potential players

et al.

1965 1970 1975 1980 1985 1990 1995 2000Year

0

2

4

6

Ab

un

dan

ce in

dex

9

9.5

10

10.5

11

11.5

12

Te

mp

era

ture

(oC

)

Dutch coastal data

Solenette

1965 1970 1975 1980 1985 1990 1995 2000Year

0

1

2

3

4

5

Ab

un

dan

ce in

dex

9

9.5

10

10.5

11

11.5

12

Te

mp

era

ture

(oC

)

Dutch coastal data

Scaldfish

Why the interest?

Lesser weever: Echiichthys vipera

- 2 0 - 1 0 0 1 0 2 0 3 0

4 0

5 0

6 0

7 0

Distribution of Lesser Weever

Azores

Canaries

Lesser Weever

Classed as sub-tropicalNot commercially exploitedVery few predators

Generally found on soft substrata BuriesSpawns June to AugustJuveniles tend to be inshore and larger adults further offshoreTends to inhabit areas <50m depth

Wheeler, A. 1978. Key to the Fishes of Northern Europe.

It has no value to fishermen or anglers, and its chief impact on man is in being one of very few dangerous fishes in European seas.

Totenese, E. 1986. CLOFNAM.

This species is considered the most dangerous of the European weevers, both for its poison and for its frequent occurrence very near to beaches.

North Sea

1. Annual changes in lesser weever distribution

2. Annual changes in lesser weever abundance

3. Changes in lesser weever length frequencies

0 5 10

50

55

60

1971

North Sea weever fish (Catch per rectangle)

0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1972


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1973


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1974


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1975


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1976


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1977


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1978


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1979


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1980


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1981


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1982


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1983


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1984


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1985


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1986


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1987


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1988


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1989


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1990


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1991


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1992


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1993


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1994


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1995


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1996


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1997


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1998


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

1999


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

0 5 10

50

55

60

2000


0 to 1

1 to 10

10 to 50

50 to 100

100 to 500

1970 1975 1980 1985 1990 1995 2000

0

10

20

30

40

50

M

ean

ab

un

dan

ce

per

sam

ple

d r

ecta

ng

le

0

5

10

15

20

25

30

No

of

rect

ang

les

con

tain

ing

wee

vers

North Sea

IBTS

1970 1975 1980 1985 1990 1995 2000 2005

0

4

8

12

16

20

Ab

un

dan

ce (

no

. ha-1

)

North SeaDutch surveys

0 5 1 0

5 0

5 5

6 0

1970 1975 1980 1985 1990 1995 2000Year

Lesser Weever: Latitude of population centre

0

2000

4000

0

2000

4000

0

2000

4000Ab

un

dan

ce

4 8 12 16Total length (cm )

0

2000

4000

1985-89

1990-94

1995-99

2000-03

Irish Sea

1. Distribution of lesser weever

2. Annual changes in population size of lesser weever

3. Annual variation in production of lesser weever

4. Changes in condition of lesser weever

Distribution of Lesser Weever in the Irish Sea

- 6 - 5 - 4 - 35 3

5 4

5 5

1 9 9 4

-6 -5 -4 -353

54

55

ENGLANDIRELAND

W ALES

SCOTLAND

IoM

Liverpool Bay

Simulated drift of plaice eggs and larvae, in the Irish Sea, after 31 and 61 days. Vertical movement behaviour patterns allowed for larvae. Data based on distribution of eggs and current patterns in 1995.Data from DEFRA/CEFAS funded research (MF0425) - plaice

Juvenile lesser weever (and plaice) and nursery grounds in the eastern Irish Sea

- 6 - 5 - 4 - 3

53

54

55

1 2

3

4

56

7

W ales

England

Scotland

Ireland

IrishSea

Zone 1Red Wharf Bay andPenmaenmawr

Zone 3Blackpool andMorecambe

1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004Year

0

10

20

30P

op

ula

tio

n s

ize

(mill

ion

s)

9 . 6

1 0

1 0 . 4

1 0 . 8

1 1 . 2

1 1 . 6

Mea

n a

nn

ual

te

mp

erat

ure

(o

C)

Lesser W eever fish in the Irish Sea

Survey data supplied by CEFAS, Lowestoft

Incom plete surveys

Lesser weevers in the Irish Sea (temperature 4 years ahead of population size)

R sq = 0.73

9 . 6 9 . 8 1 0 . 0 1 0 . 2 1 0 . 4 1 0 . 6 1 0 . 8 1 1 . 0 1 1 . 2 1 1 . 4 1 1 . 6M ean Annual tem perature (oC)

0

5

10

15

20

25

30

Po

pu

lati

on

siz

e (m

illi

on

s)

19901991

1992

1993

1994

1995

1996

1997

19981999

2000

Lesser weevers in the Irish Sea (temperature 4 years ahead of population size)

R sq = 0.73

9 . 6 9 . 8 1 0 . 0 1 0 . 2 1 0 . 4 1 0 . 6 1 0 . 8 1 1 . 0 1 1 . 2 1 1 . 4 1 1 . 6M ean Annual tem perature (oC)

0

5

10

15

20

25

30

Po

pu

lati

on

siz

e (m

illi

on

s)

19901991

1992

1993

1994

1995

1996

1997

19981999

2000

2001

2002

2003

- 6 - 5 - 4 - 3

5 3

5 4

5 5

I R I S H S E A

L e s s e r w e e v e r : L a t i t u d e o f p o p u l a t i o n c e n t r e

1988 1990 1992 1994 1996 1998 2000 2002 2004Year

53

54

Lat

titu

de

(N)

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004Year

0

10

20

30

Po

pu

lati

on

siz

e (m

illio

ns)

5 3

5 3 . 5

5 4

Lat

itu

de

of

po

pu

lati

on

cen

tre



Incom plete surveys

92-93 93-94 94-95 95-96 96-97 97-98 98-99 99-00 00-01 01-02

Years

0

100

200

300

An

nu

al P

rod

uct

ion

(g

wet

wei

gh

t p

er 1

00 in

div

idu

als)

0

200

400

600

800

1000

To

tal A

nn

ual

Pro

du

ctio

n

(to

nn

es)

1 0

1 0 . 4

1 0 . 8

1 1 . 2

1 1 . 6

Me

an

An

nu

al

tem

pe

ratu

re (

oC

)

4 8 12 16 20 24 28Population size (millions)

0.96

1

1.04

1.08

1.12

1.16

Mea

n c

on

dit

ion

Fac

tor

(K)

1992

1993

1994

1995

1996

1997

1998

1999

2000

20012002

1 0 1 0 . 4 1 0 . 8 1 1 . 2 1 1 . 6Mean Annual Temperature (oC)

0.96

1

1.04

1.08

1.12

1.16

Mea

n c

on

dit

ion

Fac

tor

(K)

1992

1993

1994

1995

1996

1997

1998

1999

2000

20012002

One final thought

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004Year

0

10

20

30

Po

pu

lati

on

siz

e (m

illio

ns)

0

4000

8000

12000

16000

Sp

awn

ing

Sto

ck B

iom

ass

(t)

Co

d



Incom plete surveys

1970 1975 1980 1985 1990 1995 2000 2005

0

10

20

30

40

50

M

ean

ab

un

dan

ce

per

sam

ple

d r

ecta

ng

le

0

50000

100000

150000

200000

250000

300000

Sp

awn

ing

Sto

ck B

iom

ass

of

Co

d

North Sea

In both areas there has been a decline in e.g. cod stocks.In both areas there has been a general increase in water temperatureIn both areas the lesser weever population appears larger than in the immediate past.

What can non-commercially exploited species tell us about climate change?

Even these species are subjected to variability driven by commercial fishing operations – difficult to disentangle climate versus other driving factors.

In many cases the data time series are too short to show clear trends in distribution, however, there are signs of increased population size of e.g. weever fish in to the North Sea.

In the case of the Irish Sea population there was a clear trend in population size with the thermal regime, however, this breaks down in more recent years.

Weever fish What the non-commercially exploited species can tell us about climate change Richard...

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