Salmon stocks and fisheries in England and Wales, 2001. Preliminary assessment prepared for ICES, April 2002

This report presents a preliminary assessment of the state of salmon stocks and fisheries in England and Wales in 2001 to assist ICES in providing scientific advice to NASCO and to provide early feedback to fishery managers and anglers. The chief indicators of the state o f salmon stocks are normally the catches taken by rod and net fisheries. However, in 2001 angling was affected by the outbreak of foot and mouth disease (FMD), which restricted angling opportunities and access to rod fisheries in many parts of the country for lengthy periods. It is impossible to quantify the impact that FMD had on rod catches, although these were undoubtedly significantly reduced; net fisheries were unaffected by FMD. The declared salmon catch for 2001 (including those fish released alive by anglers) is provisionally estimated at 209 tonnes, representing some 57,000 fish, and comprising 153 tonnes (-43,000 fish) by nets and fixed engines and 56 tonnes (-14,000 fish) by rods. For direct comparison with previous years, it should be noted that the declared catch prior to the issue of a second reminder was about 49 tonnes (see below). An estimated 26 tonnes (43%) of the rod catch was released alive. These figures do not take account of catches of salmon which go unreported (including those taken illegally), and it is estimated that there may have been a total of 33 tonnes of additional fish caught in 2001; approximately 15% of all fish killed.

根据花粉分析推论东北长白山西麓一万年来植被与环境

通过对长白山西麓山间沼泽分地钻孔沉积物孢粉的定量分析，结合对长白山植被与现代表土花粉关系的研究以及对当地现代沼泽体空间分布的调查的结果，认为该地区一万余年以来植被和环境经历了以下五个发展阶段，（1）约10300-1000年BP，森林植被为云冷杉林，洼地积水形成浅水湖泊，气候寒冷潮湿;（2）10000-9000年BP，以桦木林为主，并混生有一定数量的阔叶树，湖泊演化形成沼泽，低位苔草沼泽和中位落叶松-藓类沼泽发育，气候逐渐转暖;（3）9000-2900年BP，落叶阔叶林和阔叶红松林繁盛，落叶松—藓类沼泽进一步发育，气候温暖;（4）2900-950年BP，以阔叶红松林和红松云冷杉林为主，沼泽演化形成高位落叶松—狭叶杜香—泥炭藓沼泽，气候温凉潮湿;（5）950-0年BP，森林逐渐演化形成今日之阔叶红松林，沼泽退化为中低位苔草—藓类沼泽，气候温凉略干。

Electrophoretic and immunotaxonomic studies of three species of marine gastropods from Portonovo coast with reference to population management

Electrophoretic and serological studies of foot muscle protein of three species of Cerithiacea (Telescopium telescopium, Cerithidea fluviatilis and C. obtusum) were carried out to understand their relationships. Living specimens were collected from mud flats and mangrove swamps off Portonovo. Polyacrylamide electrophoresis of proteins from foot muscle extract of T. telescopium, C. fluviatilis and C. obtusum showed that the former had a different densitometric profile as well as more number of protein bands; but the later two species showed a closer related pattern as well as lesser number of protein bands. At the same time these two species are distinguished from each other in their total number of bands and Rf values. Immunological studies using micro-Ouchterlony double diffusion tests which absorbed antiserum indicated that C. fluviatilis and C. obtusum were more closely related as revealed by an identity reactions than T. telesopium as shown by non-identity reactions. Results are discussed in relation to ecological and morphological adaptations

Observations on the mating behavior, spawn mass and larval development of Hydatina physis Linne, 1758 (Cephalaspidea: Hydatinidae) from Karachi

Reproduction of Hydatina physis was studied in a population from Karachi, Pakistan, including mating and egg laying behavior, spawn characteristics and development.Individuals first appear in the field in October and remain until March. The spawning occurs from mid-November till mid-February with a peak in December. During this period the individuals were also observed pairing. In captivity, mating lasts for 30 minutes, second mating occurs two days later. Oviposition occurs in a very interesting and unusual manner. The mother turns "up-side-down" with its food fully expanded and the shell completely hidden underneath, the expanded foot serves as protective cover to the eggs. Eggs are deposited in a complexly folded mass with a short stem and an adhesive disc. Capsules, arranged in a single layer, contain 4-6 eggs each of wich is 70 um in diameter. Development is planktotrophic and veligers hatch after 14 days at a temperature of 26-28 degrees Celsius.

Studies on the filtration, feeding and excretion rates in Perna viridis, Marcia cor and Crassostrea gryphoides (Mollusca: Bivalvia) using P³² labelled Ankistrodesmes

The study deals with a series of experiments to investigate feeding and excretion in three species of bivalves: Perna viridis (Linné), Marcia cor (Sowerby) and Cassostrea gryphoides (Gould) from Manora Channel, Karachi. Bivalves were fed with suspensions of Ankistrodesmes labelled with P³². These animals showed a considerable variation in the average filtration rates depending upon species and the body lenght. Exceptionally high content of the P³² introduced with Akistrodesmes, got excreted as pseudofaeces and faeces within first three days following its absorption as a meal. The assimilated P³² is partly released as faecal material and its major proportion is directly transferred to the solution. As expexted the gonad and kidney are the main organs found responsible for excretion as comared to other body parts. Although, the assimilated P³² is mostly concentrated in the digestive glands, the results also show a significant presence of P³² in the gonads. Accumulation of P³² was the least in the foot.

On the effect of tickler chain on the catches landed by a 55 ft. trawl net

The communication deals with the results of comparative tests conducted from Cochin base to study the effect of a tickler chain on the catches landed by a 55' shrimp otter trawl. The net was operated with and without chain and 82 hauls of 61 hours and 28 minutes total duration were made. The following are the conclusions: (a) the catch of shrimp per hour of trawling is increased by about 71% due to attachment of the chain to the ground rope; (b) the attachment of the tickler chain also increased the catch of fish by 25%. The increase in the catch of shrimps and fish is probably due to the disturbance caused by moving chain attached to the foot-rope.

Assessment and possible development of the fishery resources of Pedro Bank

Pedro Bank is about 1,300 square miles in extent and lies at the mouth of the Palk Strait close to the mainland, enabling smaller boats to exploit it. Trawl surveys indicated the presence of substantial demersal varieties on the Pedro Bank, but the results of the early commercial operations indicate that a 135-foot trawler may not be operated continuously on the bank without diminishing returns. Subsequent to the commercial operations extensive surveys with smaller boats and various types of gear were carried out. Of the various types of gear tried out, results from bottom long lining and hand lining operations were promising. Trials were carried out to compare these two types of gear. Though not extensive, these trials indicated that at the initial stages of exploitation of the Bank, hand lining, which is extensively practiced in Ceylon, may be better but as exploitation progresses; with more experience, it should be possible to overcome some of the present disadvantages of bottom long lining and eventually bottom long lining should produce better results. The recently introduced mechanised craft are exploiting only the fringe of the bank and it should be possible to exploit its stocks fully with slightly bigger boats with a 35-40 mile range.

The Pearl Banks inspection: April, 1970

The last major pearl fishery in the Gulf of Mannar was held in February-March, 1958, when about 4.5 million oysters were collected from the south-west Cheval Paar by dredging. (Sivalingam 1961). Subsequently, two smaller fisheries, one in 1960 and another in 1961 took place. In these two fisheries one million oysters and four hundred thousand oysters respectively were collected from the Cheval paar by dredging. (De Fonselm 1953). Inspections of the Banks were carried out in 1962, 1963, 1964 and 1965. (Balasuriya 1964 and Silva 1965 and 66). Since then inspections were not possible due to one of two reasons or both the non-availability of operational dredges and a suitable vessel for this type of work.The "Pesalai" a 235-ton stern trawler was made available by the Ceylon Fisheries Corporation management for the 1970 inspection. Two new 6-foot dredges turned out by the Government Factory were also available for this work. However, the survey was limited to 3 days-the period for which the vessel had been released. It was further limited to those areas of the banks over 6 fathoms in depth because of the risk in operating a large vessel in shallower depths.

Economics of operation of 38' G.R.P. fishing vessels issued by the A.D.B. Fisheries Project: a case study

The author gives a financial and economic valuation of the operation of vessels in the 38 foot GRP class. He discusses particularly the materials and methods of fishing they use, species composition of their catches, their rate of return, break-even analysis, financial and social analysis.

Role of the state and financial institutions in financing the fishing industry

The experience of the Government in the recovery of loans for 28 foot mechanized vessels has been unsatisfactory. The author examines the various aspects which have contributed to this situation, and considers arrangements for financing purchase of such vessels. The risks associated with the investment in 38 foot vessels are high, and it seems that the reluctance of private investors to make the required contribution from personal funds is a result of fear of the unknown. Current incentives provided by the Government to the private sector for the purchase of 38 foot vessels are considered to be adequate.

Financial assistance for purchase of large fishing vessels

The Government of Sri Lanka is improving off-shore and deep-shore fishing by introducing more sophisticated and larger vessels into the Sri Lanka waters, together with the offer of subsidies, tax holidays and other concessions to those who seek to operate such fishing vessels. As a first step, some thirty 38 foot class fishing vessels are to be introduced. The requisite variety and quantity of fishing gear is supplied together with the vessels, and operators will be given further assistance to either export or market their catches locally by provision of insulated fish transport vans, jeeps with trailers, crushed ice plants, fish storage cabinets and adequate spares for at least the next few years. A description is given of the credit terms offered for the purchase of such vessels, pre-shipment finance, and loans and hire purchase facilities.

The morphometrics and the proximate composition of the edible fresh water mussel Lamellidens lamellatus (Lea) from Bathalagoda tank, a man made reservoir in Sri Lanka

Morphometric characteristics of Lamellidens lamellatus were studied using a random sample of 138 individuals collected from Bathalagoda reservoir in Kurunegala district. The largest number of individuals in the collection was between 40-50 mm in length. They had a body weight between 60-80 gm. The most abundant bio-chemical component in the adductor and in the foot was protein. Carbohydrate and lipid quantities were almost equal while ash showed the least value. The total protein content ranged from 48.8% to 73.4%; the carbohydrate content from 12.64% to 23.8%; and lipid content from 12.0% to 28.1% of their dry weight. It was found that there were significant relationships between the length and the body weight; and between length and volume.

Development of electro-trawl system in marine environment

High voltage pulsed current produced on board a trawler is fed to electrodes distributed along the foot rope of a trawl net through two core TRS cable which builds up a homogeneous electrical field around the net mouth. By comparative fishing tests with the electrified and non-electrified 32 m long wing trawl net, the increase in total catch of shrimps and fishes was found to be 19.8 and 36%, respectively.

Twin trawling for shrimp with dummy doors

Twin trawling; a new concept in shrimp trawling is described in this paper. It essentially involves towing of two trawls of equal size connected in sequence at the inner head and foot rope legs and using a pair of outer otter boards and central neutral door or dummy door with triple bridles and single tow warp. A comparative study with conventional stern trawling using a standard 13.7 m four seam shrimp trawl and two 6 8 m standard four seam trawls as twin-rig has shown considerable reduction in the utilization of power (20 %) with better efficiency in shrimp fishing.

Both stress experience and age determine the impairment or enhancement effect of stress on spatial memory retrieval

It has been documented that stress or glucocorticoids have conflicting effects on memory under different conditions. However, it is not fully understood why stress can either impair or enhance memory. Here, we have examined the performance of six age groups of Wistar rats in a water maze spatial task to evaluate the effects of stress under different conditions. We found that the impairment or enhancement effect of an 'elevated platform' (EP) stress on memory was dependent on previous stress experience and on age. EP stress impaired memory retrieval in water maze naive animals. but enhanced rather than impaired memory retrieval in young water maze stress-experienced animals. Furthermore, exogenously applied corticosterone or foot shock stress before water maze training prevented the impairment of memory retrieval that should be induced by treatment with corticosterone or foot shock before the 'probe trial'. Again, memory retrieval was enhanced in young animals under these conditions, and this enhancement can be prevented by the glucocorticoid receptor antagonist RU 38486. Thus, glucocorticoid receptor activation not only induced impairment of memory but also increased the capacity of young animals to overcome a later stress. The present findings suggest that the effect of stress on memory can be switched from impairment to enhancement dependent on both stress experience and age.