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Variation in length, girth and weight of large northern pikes(Esox lucius) in FinlandAuthor(s): Marco Milardi Jyrki Lappalainen & Teppo JuntunenSource: Annales Zoologici Fennici, 51(3):335-339. 2014.Published By: Finnish Zoological and Botanical Publishing BoardDOI: http://dx.doi.org/10.5735/086.051.0305URL: http://www.bioone.org/doi/full/10.5735/086.051.0305

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Ann. Zool. Fennici 51: 335–339 ISSN 0003-455X (print), ISSN 1797-2450 (online)Helsinki 30 June 2014 © Finnish Zoological and Botanical Publishing Board 2014

Variation in length, girth and weight of large northern pikes (Esox lucius) in Finland

Marco Milardi*, Jyrki Lappalainen & Teppo Juntunen

Department of Environmental Sciences, Aquatic Sciences, P.O. Box 65, FI-00014 University of

Milardi, M., Lappalainen, J. & Juntunen, T. 2014: Variation in length, girth and weight of large northern pikes (Esox lucius) in Finland. — Ann. Zool. Fennici 51: 335–339.

The relationship between total length (L, cm) and weight (W, kg) in the large northern pike (Esox lucius) was investigated using a dataset comprising 802 specimens weigh-

the equation W = aLb a = 6.648 ¥ 10–6 and b -

G, cm) — W = aGb and W = a(L ¥ G)b

W = aLb and W = aGb showed that weight

W = a(L ¥ G)b

with the parameters a = 2.426 ¥ 10–3 and b

Introduction

The northern pike (Esox lucius) is the most

Sea (Rask et al.

-

-

-

is used during the open-water period, whereas -

336 Milardi et al. ANN. ZOOL. FENNICI Vol. 51

et al. 2004).

large-sized northern pike, including also large individuals weighing more than 10 kg, which,

also compared with the ordinal date, starting

-ing. Northern pikes spawn in shallow waters

-

weight during spring months.

Material and methods

-

-

-

also available, was chosen to estimate weight in relation to length and girth. These data sets con-

-

-

The relationship between total length (L, cm) and weight (W

W = aLb, (1)

procedure without random variables and speci-

-pared weight residuals with the ordinal date, based on the assumption that gonad weight loss

would occur in a limited time window.

-tionships between length–weight residuals and

in which ineighbourhoods centred on a predictor value x

i,

xi. A smoothing parameter

determines the neighbourhood size used and here

selection criterion based on the unbiased selection

A weight estimation method was subse-

-

G

W = aGb, (2)

ANN. ZOOL. FENNICI Vol. 51 Length, girth and weight of large northern pikes 337

W = a(L ¥ G)b (3)

(Esox masquinongy

an estimation criterion to compare the gain in

Results

relationship between weight and length (Eq. 1) ¥ 10–6

a bspecimens in our sample could be considered

about 100 cm in total length whose weight

measurements, however, were removed as these

Table 1. Lengths and weights of northern pikes in different datasets.

Dataset Mean weight (kg) (min–max) Mean length (cm) (min–max) n

SVK 11.8 (10–18.8) 115.1 (100–131) 247POKA + SHS 06.2 (1–14) 093.7 (42–123) 555LGW subset of SVK 11.8 (10–18.8) 115.5 (100–131) 186All data 07.9 (1–18.8) 100.3 (42–131) 802

0

2

4

6

8

10

12

14

16

18

20

40 60 80 100 120 140

Wei

ght (

kg)

Length (cm)Fig. 1. Relationship between length and weight in large-sized northern pike (n = 802).

–6

–4

–2

0

2

4

6

8

00 50 100 150 200 250 300 350

Res

idua

l wei

ght (

kg)

Ordinal dateFig. 2. Weight residuals from the relationship between length and weight (Eq. 1) against ordinal date number when northern pikes were caught. The line is based on the Loess smoothing procedure.

-

338 Milardi et al. ANN. ZOOL. FENNICI Vol. 51

Discussion

-

that were more than 14 kg, being heavier than

measurement errors (e.g. due to imprecise scales -

prising the largest northern pikes, however, con-

scales and whose total lengths were measured

length measurements should be more prone to errors due to scale inaccuracies.

This relationship when applied to the whole dataset did not appear to be able to describe

-

-

Table 2. Parameters a and b in the length–weight relationship (Eq. 1) for the whole dataset, and comparisons of AIC values and parameters a and b for Eqs. 1, 2 and 3 in a subset of data in which maximum girth was measured.

Dataset Relationship a b AIC value AIC n

SVK + POKA + SHS LW (Eq. 1) 6.648 ¥ 10–6

LGW subset LW (Eq. 1) 0.004859 1.6417 690.0 0.0 186LGW subset GW (Eq. 2) 0.204450 1.0224 624.9 –65.1 186LGW subset LGW (Eq. 3) 0.002426 0.9739 566.3 –123.7 186

910111213141516171819

90 100 110 120 130 140

Wei

ght (

kg)

Length (cm)

910111213141516171819

30 40 50 60 70 80

Wei

ght (

kg)

Girth (cm)

910111213141516171819

4000 5000 6000 7000 8000 9000

Wei

ght (

kg)

Girth x Length (cm2)

a

b

c

Fig. 3. (a) Length, (b) maximum girth and (c) maximum girth ¥ length in relation to weight in large northern pikes (n = 186).

¥ 10–3 a b -

ter a p

ANN. ZOOL. FENNICI Vol. 51 Length, girth and weight of large northern pikes 339

-ted weight residuals against the ordinal date

during spring, which is consistent with previ-

taken into account as it could be an important

versus

or stomach contents. Also, using more than one

smaller residuals.The length–weight–girth relationship pre-

-a =

4.18 ¥ 10 and b = 1.441) and those calculated

a = 0.007 (in grams) and band a = 0.001–0.021 and b = 2.723–3.411 (min–

length–weight relationship estimated based on

Since measuring a precise weight (or gutted

-ments seems a viable approach.

Acknowledgements

References

Esox lucius). — Folia Zoologica

Esox lucius Journal of Fish Biology

-

— American Fisheries Society Special Publication

Esox lucius). — Canadian Journal of Fisheries and Aquatic Sciences

Journal of the American Statistical Associa-tion

Esox lucius Journal of Animal Ecology

. — Available at

series model selection in small samples. — Biometrika

-

Climate Research

Nordic Hydrology

Esox luciusrivers in southern England. — Journal of Fish Biology

Esox lucius

Hydrobiologia

Fish Status Survey of Nordic Lakes – species composition, distribution, effects of environmental changes.

, 2nd