Retaining employees has emerged as a key business challenge in a market where many important commercial, technical and management skills are in such short supply. This issue isn't just high on the agenda for the human resources (HR) department; it is also becoming a point of discussion among senior managers and in the boardroom.

Every time you lose a good employee, it costs you money because you'll need to recruit and train someone to replace him or her. It disrupts continuity in your business, can hurt customer relationships, slows you down, and results in you losing a small piece of your corporate memory.

Yet only 7% of respondents to Deloitte's Global Human Capital Trends 2015 survey consider themselves excellent at measuring, driving, and improving engagement and retention. Here are some powerful strategies for retaining your top-performing team members.

1. Keep investing in training, development and mentoring

Employees place a high value on opportunities to develop their skills and learn new things, and that's doubly true of the most ambitious, high-performers that could become your business's future leaders. For that reason, it's important to have a formal learning and training strategy, and to keep budget available for training and development. Even when times are tough, training should be one of the last places you look when you're trying to reduce costs. Losing good people or having an unskilled workforce will cost your business more money in the longer term.

2. Invest in employee engagement

Employee engagement can be defined as the techniques, tools and strategies you can use to get employees motivated about their work and engaged in the business's strategy, values and culture. Some examples of these include employee satisfaction surveys, employee self-service tools, team-building exercises, and mentoring processes. Without this investment, the business and its employees will be in poor alignment. The result will be poor staff retention.

3. Hire and promote the right people for the job

One of the biggest reasons people don't last in a job is that they weren't a right fit for the role or the company in the first place. Evaluate every candidate for his or her cultural fit with your organisation – don't just look at the skills, qualifications and experience, but also assess his or her attitude, values and outlook. A person might be a great hire for another business, but not for yours, simply because of cultural fit. Also, be sure to check that you're hiring (or promoting) the person for the right job. A candidate could be a spectacular salesperson and a terrible manager.

4. Listen to employees and ask for feedback

It's important to gather employee feedback through formal and informal channels alike. Conduct regular surveys to assess workplace happiness and find out what you can realistically do to improve employee satisfaction. Also, make time to listen to employees' suggestions in more informal settings.

Even though not every suggestion will be viable to implement and some complaints might not be valid, people like to feel that their opinions are heard and their issues are understood. Employees might have great suggestions that can help you improve your business – their perspectives can be invaluable.

5. Empower mobile and remote workers

Mobile technologies allow people to be productive wherever they are. However, working practices at many organisations have yet to catch up. These days, the best people gravitate towards organisations that offer them the work-life balance they desire.

Rather than enforcing rigid office hours, why not allow knowledge workers who can do their jobs anywhere to work remotely or keep more flexible hours? Long commutes in traffic are the source of much misery for the workforce, so it seems sensible to adopt working practices that help people spend their time as productively as possible.

6. Transparent performance management

A formal performance management process brings fairness and transparency into your relationship with employees. It helps them understand what is expected of them and helps you to understand what their goals are. Employees who know what they are working towards will be happier and less likely to leave than those who feel uncertain about what their goals and those of the company are.

7. Communicate clearly

It's important to keep employees as well informed about activities within the business as you can. Too much secrecy can eat away at employees' happiness, trust, and confidence, leading to staff turnover. Rather be as transparent about the business's plans, opportunities, and challenges as you can within the constraints of stock market regulations, customer confidentiality agreements, and so forth. Even when there's bad news, it's better to be upfront about it and give employees certainty.