Dating ranging from fishing capabilities and give at every model

Dating ranging from fishing capabilities and give at every model

Figure step 3. 20 years simulation of count in the inventory Letter and you will money Rev whenever carrying capacity K fluctuated. Built-in rate of growth roentgen was lingering (0.8) and you will a great = 5.

Contour 4. A: K are ongoing (15000), roentgen fluctuated away from 0.dos because of 1.4 and you can F is actually set-to r /2. B: K are ongoing, r fluctuated and you will F was set-to lingering (0.4). C: K fluctuated and you will roentgen try constant (0.8). Right here, fishing skill is actually increased because of the q and you may produce are split from the one hundred.

The newest bionomic balance point off F where Prof =0 from the reasonable stock height F eq (low) ( K =5000, roentgen =0.8) and you may high stock level F eq (high) ( K =twenty-five 100, r =0.8) regarding condition that a good = 5 was indeed 0.08 and you may 0.66, respectively (Dining table step one). Speaking of comparable to 160 and you may step 1 320 (boat*trips) in fishing capacity, respectively, and equal to full (40) travel by the four and 33 ships.

4.2 Action during the r

A couple compile steps have been checked on the situation when carrying capability, K , are constant and you may built-in growth rate, roentgen , fluctuates, i.elizabeth. let F feel constant and you will F end up being r /dos in order to satisfy changing roentgen .

The newest bionomic balance part from F where Prof =0 on lower inventory top F eq (low) ( K =15 100000, roentgen =0.2) and you can large stock peak F eq (high) ( K =15 000, roentgen =1.4) regarding the reputation one to a beneficial = 5 and you may b = dos were 0.15 and 0.99, respectively (Dining table 1). He could be equivalent to three hundred and you may 1980 (boat*trips) within the angling capability, respectively, and equivalent to complete (40) trips from the eight.5 and forty two.5 ships.

The partnership anywhere between Letter and Y , and you can F and you will Y whenever r is the minimal and you will restriction from certain variety and you will carrying capability K is ongoing are shown for the Profile 5. Enough time variety of stock size Letter , give Y and cash Rev playing with non-balance manufacturing model are offered inside Figure six. The fresh give became maximum whenever F = 0.52 and therefore equivalent to full (40) cruise because of the 26 boats (Contour cuatro). The gains turned into restrict whenever F = 0.24 and that equal to complete (40) cruises by a dozen vessels on the status one to an excellent = 5 (Desk 1 and you may Fig. 8).

Contour 6. Two decades simulator of Letter , Y and you can Rev when K was lingering (15000) and you can a great = 5. roentgen fluctuated from 0.2 to one.cuatro but F is set to 0.4.

The full time a number of stock dimensions Letter , produce Y and you may cash P rof making use of the dynamic development design are given from inside the Contour seven. Within this approach, F fluctuates annual but you should never go beyond the upper restrict add up to the fresh new fishing strength place in progress. This case is the ideal attain means, as F reacts to the actual possessions away from fish the newest inventory. It is necessary so that way too much fishing effort are still by the closing of fishery whenever F should be smaller due to a great reasonable progress requirements.

Figure seven. Twenty years simulator from Letter , Y and you can Rev whenever K is ongoing (15 100) and you will an effective = 5. r fluctuated away from 0.2 to a single.4 and F changed properly ( F =r/2), but fishing ability try limited 800 (boat*trips).

Matchmaking between Letter and you can Y (left committee) and you will F and Y (right panel) whenever carrying potential K alter 5000 and you will 25000 in the Schaefer model

About simulator revealed when you look at the Figure eight, the latest stock proportions gradually converged to K /2 (=7 five hundred), the fresh inventory proportions you to definitely reaches MSY. The outcome when angling capability is higher than step 1 eight hundred (boat*trips) produced yield restriction (Profile cuatro). Angling death from, matches a full use of fishing capabilities of just one 400 (boat*trips), that is equal to F MSY (high), which is also equivalent to an entire number of travel because of the thirty-five ships. Fishing mortality F you to generated the gains restrict varied with a great . Whenever an effective = 5, F = 0.thirty-six (full vacation by 18 ships) generated the earnings restriction, when you find yourself F = 0.31 (complete cruise trips from the fifteen vessels) when an effective = ten, and you can F turned into smaller due to the fact a great increased (Figure 8).

Deixe um comentário

O seu endereço de e-mail não será publicado.