11.06.2015 Views

Lakes and Watercourses

Lakes and Watercourses

Lakes and Watercourses

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

TABLE 47.<br />

CALCULATION OF REFERENCE VALUES for lakes.<br />

Parameter Height (m) Reference value<br />

Number of fish species 1 0 – 100 J = 2.44 · Lake area 0.233<br />

101 – 300 J = 2.07 · Lake area 0.218<br />

> 300 J = 1.68 · Lake area 0.171<br />

Species diversity 2 all J = –0.0414 + 0.331 · ln (No. of fish species)<br />

Weight per effort 3 0 – 100 J = 3981 · Maximum depth –0.383<br />

101 – 300 J = 2511 · Maximum depth –0.383<br />

> 300 J = 1995 · Maximum depth –0.383<br />

Number per effort 3 0 – 100 J = 77.0 – 35.6 · log 10 (maximum depth)<br />

101 – 300 J = 36.0 – 13.1 · log 10 (maximum depth)<br />

> 300 J = 19.8 – 6.1 · log 10 (maximum depth)<br />

Proportion of piscivorous percids 4 all J = 0.481 – 0.0000615 · (total weight/effort)<br />

Proportion of piscivorous cyprinids 5 all J = 0.283 + 0.0000694 · (total weight/effort)<br />

1 Only fish species native to Sweden are included (see list of species). Lake area is expressed in<br />

hectares.<br />

2 Species diversity is calculated as Shannon-Wiener’s H’ = [W tot log 10 (W tot ) – ΣW i log 10 (W i )] / W tot<br />

where W tot is the total weight per effort <strong>and</strong> W i is the weight per effort for each species.<br />

3 Biomass <strong>and</strong> number are expressed as grams <strong>and</strong> number per effort, respectively. An effort constitutes<br />

one night’s fishing with a net using a st<strong>and</strong>ard method. Depth is expressed in metres.<br />

4 Piscivorous percids includes z<strong>and</strong>er (S<strong>and</strong>er lucioperca) <strong>and</strong> perch (Perca fluviatilis) more than<br />

150 mm in length. The parameter is only calculated for lakes where perch <strong>and</strong>/or z<strong>and</strong>er are<br />

caught.<br />

5 The following species are classified as cyprinids: asp (Aspius aspius), bleak (Alburnus alburnus),<br />

silver bream (Abramis bjoerkna, alt. Blicca bjoerkna), bream (Abramis brama), minnow (Phoxinus<br />

phoxinus), Zope (Abramis ballerus), ide (Leuciscus idus), roach (Rutilus rutilus), crucian carp<br />

(Carassius carassius), rudd (Rutilus erythrophthalmus, alt. Scardinius erythrophthalmus), dace<br />

(Leuciscus leuciscus), tench (Tinca tinca) <strong>and</strong> Baltic vimba (Abramis vimba alt Vimba vimba).<br />

The parameter is only calculated for lakes where cyprinids are caught.<br />

77

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!