Target Length Calculator
This operator creates a single target variable that reports the calculated target length of each detected target.
It accepts operands with the following data types:
- Single targets
Notes:
- This operator is intended for use with single beam data. Target length in multibeam data is calculated and displayed differently, via the Multibeam target detection operator and the Target conversion operator.
- Target lengths from a single target echogram
- About target properties
Settings
The Target Length Calculator Variable Properties dialog box pages include (common) Variable Properties pages and these operator pages.
Operands page
Target length page
|
Setting |
Description |
|
Factor A |
Enter the species specific factor A. |
|
Factor B |
Enter the species specific factor B. |
Algorithm
The Target length calculator operator estimates Target length (L) in cm from target strength (TS) using two species specific constants A and B, and is calculated using the (inverse of the following) equation:
TS = A log(L) + B
The table below lists values of A and B for some fish species.
|
Species |
A (Slope ) (dB) |
B (Intercept) (dB) |
|
Basketwork eel (Diastobranchus capensis)1 |
20.1 |
-70.1 |
|
Black javelinfish (Mesobius antipodum)1 |
25.9 |
-84.5 |
|
Javelinfish (Lepidorhynchus denticulatus)1 |
20.0 |
-73.5 |
|
Black oreo (Allocyttus niger)1 |
14.9 |
-62.1 |
|
Smooth oreo (Pseudocyttus maculatus)1 |
27.6 |
-87.7 |
|
Notable rattail (Caelorinchus innotabilis)1 |
35.8 |
-93.9 |
|
Serrulate rattail (Coryphaenoides serrulatus)1 |
34.6 |
-93.8 |
|
Four rayed rattail (Coryphaenoides subserrulatus)1 |
26.3 |
-84.6 |
|
Ridge scaled rattail (Macrourus carinatus)1 |
27.9 |
-80.8 |
|
White rattail (Trachyrincus aphyodes)1 |
28.8 |
-80.2 |
|
Robust cardinalfish (Epigonus robustus)1 |
34.4 |
-83.6 |
|
Deepsea cardinal fish (Epigonus telescopus)1 |
34.6 |
-86.6 |
|
Johnson’s cod (Halargyreus johnsoni)1 |
22.5 |
-70.3 |
|
Ribaldo (Mora moro)1 |
21.7 |
-66.7 |
|
Hake (Merluccius australis)1 |
27.1 |
-83.5 |
|
Hoki (Macruronus novaezelandiae)1 |
18.0 |
-74.0 |
|
Orange roughy (Hoplostethus atlanticus)1 |
16.2 |
-74.3 |
|
Walleye pollock2 |
20 |
-66 |
|
Cod at 38kHz3 |
24.6 |
-60.8 |
|
Sprat at 38kHz3 |
17.2 |
-66.6 |
|
White perch4 |
26.48 |
-69.45 |
|
Striped bass4 |
15.37 |
-56.26 |
|
Yellowfin tuna (Thunnus albacares)5 |
34.0 |
-92.5 |
References:
- McClatchie, S. and Coombs, R.F. (2005) Low target strength fish in mixed species assemblages: the case of orange roughy. Fisheries Research 72: 185–192
"Data for all species except hoki and orange roughy are derived from swimbladder modelling (Macaulay and Grimes, 2000; Macaulay et al., 2001, 2002). The hoki TS–length regression was calculated from a combination of in situ and swimbladder data (Macaulay, 2001). The slope for the orange roughy TS–length regression was derived from experiments with live fish (McClatchie et al., 1999), with a slope adjusted using results from Barr (unpublished data)."
These values were modeled using a frequency of 38kHz. - Foote, K. G. and Traynor, J. J., (1988) Comparison of walleye pollock target-strength estimates determined from in situ measurements and calculations based on swimbladder form. Journal of the Acoustical Society of America, 83: 9–17.
These measurements and calculations were carried out at a frequency of 38kHz. - Nakken, O. and Olsen, K. (1977) Target strength measurements of fish. Rapp. P.-V. Réun. CIEM, 170:52-69
These measurements were carried out at a frequency of 38kHz. - Hartman K. J. and Nagy B. W. (2005) A target strength and length relationship for striped bass and white perch. Transactions of the American Fisheries Society: vol. 134 (2), pp. 375-380
These measurements were carried out using a 120kHz split beam echosounder. - Long-Jing Wu, Wei-Cheng Su, Jiun-Chern Lin and Le-Min Chen, (2002) Determination of in situ target strength of Yellowfin Tuna (Thunnus albacares) aggregated around sub-surface fish aggregating devices by acoustics. J. Fish. Soc. Taiwan 29 (4)
The relationship between in situ TS and fork length of yellowfin tuna.