**Abundance index (U) **- A characteristic preferably
proportional to the available biomass of the resource. The catch per unit
effort, **cpue** (especially when the effort is expressed in appropriate
units) is an important index..

**Biological Limit Reference Point (LRP) **- Biological
reference point indicating *limits* of the fishery exploitation with regard
to stock self-reproduction, aiming at conservation of the resource.

**Biological Precautionary Reference Point (PaRP)** -
biomass levels (**Bpa**) and fishing levels (**Fpa**), established under
the precautionary principle, concerning the reproduction of the stock, aiming at
conservation of the resources. The assumptions and methods used to determine the
PaRPs should be mentioned.

**Biological Reference Point (BRP) **- Values of **F**
and **B**, taking into consideration the *best possible catch* and/or
ensuring the *conservation* of the fishery resource. There are BRPs based
on long term projections (LP), BRPs based on values observed during a certain
period of years and BRPs based on the two previous criteria. The BRPs can be
*Target-Points (TRP),* *Limit-Points (LRP), and Precautionary Points
(PaRP*). In this manual the following biological reference points are
referred to: **F _{max}, F_{0.1}, F_{high},
F_{med}, F_{MSY}, F_{loss}, F_{crash},
B_{max}, B_{0.1}, B_{med}, B_{MSY},
B_{loss}, MBAL. **Other biological reference points, used in
management, like

**Biological Target Reference Point (TRP) **- Biological
reference point indicating long term o*bjectives* (or targets), for the
management of a fishery, taking into consideration the *best possible
catch* and ensuring the conservation of the stock.

**Biomass (B) **- Weight of an individual or a group of
individuals contemporaneous of a stock.

**Capturability Coefficient (q)** - Fraction of the biomass
that is caught by unit of fishing effort.

**Carrying capacity** **(k)** - Capacity of the
environment to maintain the stock living in it. It is, theoretically, the limit
of the non exploited biomass (see intrinsic gross rate of the biomass,
**r**).

**Catch in number (C)** - Number of individuals
caught.

**Catch in weight **or** Yield (Y)** - Biomass of the
stock taken by fishing. Yield does not necessarily correspond to *landed
weight*. The difference between the two values, yield and landings, is mainly
due to *rejections to the sea* of part of the catch which, for some reason
(price, quality, space problems or even legal reasons), is not landed.

**Cohort **- Set of individuals of a fishery resource born
from the same spawning.

**Exploitation pattern of a gear (s) - **Fraction of the
individuals of a given size, available to the gear, which is caught. Also
designated by *Selectivity *or* partial recruitment.*

**Individual growth coefficient (K) **- Instantaneous
relative rate of change of a function of the individual weight, w, that is**,
H(w _{∞})-H(w),** where

**Individual Quota (IQ)** - Quota attributed to a
vessel.

**Individual Transferable Quotas (ITQ) **- System of
fisheries management characterized by the sale, at auctions, of the fishing
annual vessel quotas.

**Minimum Biomass Acceptable Level (MBAL) **- Biological
reference limit point that indicates a spawning biomass level under which the
observed biomasses during a period of years, are small and the associated
recruitments are smaller than the mean or median recruitment.

**Number of individuals** **of a cohort or of a stock
**(**N) **- Number of survivals of a cohort (or a stock) at a certain
instant or over an interval of time.

**Partial** **recruitment** - (see exploitation
pattern)

**Precautionary principle** - This principle establishes
that a lack of information does not justify the absence of management measures.
On the contrary, management measures should be established in order to maintain
the conservation of the resources. The assumptions and methods used for the
determination of the scientific basis of the management should be
presented.

**Production models **- Models that consider the biomass of
the stock as a whole, that is, they do not take into consideration the age or
size structure of the stock. These models are only applied in analyses that
consider fishing level changes, as they do not allow the analysis of the effects
of changes in the exploitation pattern, on catches and biomasses.

**Quota (Q)** - Each of the fractions in which the TAC was
divided**.**

*RATES*

**Absolute Instantaneous Rate of y, air(y) **- Velocity of
the variation of the function **y(x)**, at the instant **x**.

**Absolute Mean Rate of y, amr(y) **- Mean velocity of the
variation of the function **y(x),** during a certain interval of
**x**.

**Annual Survival Rate** (**S) **- Mean rate of
survivals of a cohort during one year, relative to the initial number.

**Exploitation Rate (E) - **Ratio between the number of
individuals caught and the total number of individuals dead, over a certain
period of time, that is, **E = C/D**.

**Fishing mortality instantaneous rate (F) (Fishing mortality
coefficient) **- Relative instantaneous rate of the mortality of the number of
individuals that die due to fishing.

**Intrinsic rate of the biomass growth ®** - Constant of
the *Production models *that represents the instantaneous rate of the
decreasing of the function **H(K)-H(B)**, where **B** is the biomass,
**H(B)** is a function of the total biomass, usually a power-function,
(including the logarithmic function that can be considered a limit power
function) and **k **is the** carrying capacity** of the environment. Some
models introduce one more parameter**, p**, which is used to obtain a more
general relation.

**Natural mortality instantaneous rate** **(M)
**(Natural mortality Coefficient) - Instantaneous relative rate of the
mortality of the number of individuals that die due to all causes other than
fishing.

**Relative instantaneous rate of y, rir(y) **- Velocity of
the variation of the function **y(x),** relative to the value of **y,** at
the instant **x**.

**Relative mean rate of y, rmr(y)** - Mean velocity of the
variation of the function **y(x)** relative to a value of y, during a certain
interval of **x**.

**Total mortality instantaneous rate (Z)** (**Total
mortality coefficient) **- Relative instantaneous rate of the mortality of the
number of individuals that die due to all causes. **Z**, **F** and
**M** are related by the following expression: **Z=F+M**.

**Recruitment to the exploitable phase (R)** - Number of
individuals of a stock that enter the fishery area for the first time each
year.

**Selectivity** - (see exploitation pattern)

**Spawning **or** adult** **biomassa** **(SP) **-
Biomasss of the stock (or of a cohort) which has already spawned at least
once.

**Stock **- Set of survivals of the cohorts of a fishery
resource, at a certain instant or period of time. It may concern the biomass**
**or the number of individuals.

**Stock-Recruitment (S-R) relation **- Relation between the
parental stock (spawning biomass) and the resulting recruitment (usually the
number of recruits to the exploitable phase). The models have two constants,
**α **and **k**.** **The constant** k*** *has the physical
dimension of weight and **α** has the dimension of weight^{-1}.
Some models introduce one more parameter,** c**, which is used to obtain a
general relation that includes the most common relations.

**Structural models** - Models that consider the structure
of the stock by ages or sizes. These models allow one to analyse the effects on
catches and biomasses, due to changes in the fishing level and exploitation
pattern.

**Total Allowable Catch (TAC)** -** **Management measure
that limits the total annual catch of a fishery resource, aiming to indirectly
limit the fishing mortality. The TAC can be divided into *Quotas (Q) *using
different criteria, like countries, regions, fleets or vessels.

**Total number of deaths** (**D) **- Total number of
individuals that die during a certain period of time.*.*

**Virgin biomass (VB) **- Biomass of the stock not yet
exploited.